What's up, everyone! This is GKC here bringing you a new crossover between Fate Grand Order and Kamen Rider Geats.

Now for the disclaimer: I do not own, except my OCs, Kamen Rider or the Fate series. All rights belong to their respective owners.

Now let's get this party started… BEGIN!

Edit: I fixed that little mistake, Eduardo. Thank you for pointing that out.

Mission 1: Singularity F: The Highlight of the Fox

They say that the path to one's happiness is by finding your own desire.

To reach out and to grasp it with your own hand.

However, in other cases, it is even necessary to fight for your desires…

…and to kill as well as die for it.

"It is nearly time." A figure dressed in red robes and wearing a white suit with an intricate skull-like mask remarked. "Are you sure that they are ready?"

"If they were not ready, you would not have chosen them for this mission," Approaching the masked figure is a rather lovely woman dressed in black and white, carrying a clipboard. "For the World to be saved and Humanity to prevail, they must become its heroes."

The masked figure looked up, hidden eyes gazing deeply at a golden light that hovered gently above their heads. "The Holy Grail War. A hedonistic ritual brought up as a tournament between seven magi and their summoned familiars known as Servants. Hmph, even the DGP was hardly this bloody."

The woman smiled, "And yet, you are determined to use the DGP to help them."

The masked figure chuckled, "It seems you have managed to learn more of my mannerisms after all these years."

"It took a while but I'm learning." The woman replied. "But even I must admit that this is a risky move on your part."

"Indeed, it certainly is. But I've taken many risks in my life. Not only that, but I have faith that these individuals chosen by fate will become those that shall protect the World and humanity." The masked figure then gave the woman a hidden smirk and did a gesture with their left hand that mimicked a canine. "After all, the greatest tricks come from a fox."

The smell of smoke and fire filled the air within the ruins of a once great city that had suffered from what could only be a great disaster.

Buildings reduced to rubble, streets charred and cracked, and cars turned into nothing but smoldering wrecks.

This city had once been known as Fuyuki and it is currently the source of a great disturbance that had once been a ritual called the Holy Grail War.

It was strange…

Her newfound status as a Demi-Servant had been rather confusing yet necessary considering the sabotage that critically injured the other Masters, save for her own and his sister. She had been injured from the debris and would've surely died had it not been for the intervention of a Heroic Spirit that had lost his connection to the world and offered to save her life by granting her his abilities as a Servant.

Her arrival in Singularity F along with her Master was successful, along with the added addition of Fou and her senpai's elder sister. Unfortunately, her Master had already been attacked from afar by what she believed to be an Archer-class Servant. Thankfully, she managed to protect him and get her friends away from the threat. Unexpectedly, they also came across the Director, who seemed to have Rayshifted with them to the Singularity.

"I still can't believe that this is what you look like as a Demi-Servant, Mash." Asuka Fujimaru, her senpai's elder twin sister despite the differences in their eye and hair color since her Master's hair was black with blue eyes while Asuka had auburn hair with amber eyes.

"Yeah, I can't believe it either." Ritsuka said, looking at said Demi-Servant. "And your shield, like holy crap! You can carry that like it's 5 lbs.!"

Mash's cheeks flushed pink from the praise of both twins, "I-It's nothing special, senpai."

"I concur." Director Olga interjected with a huff, "It's only natural that Servants, even Demi-Servants, would be stronger physically than a regular human. Even modern mages have difficulties compared to Heroic Spirits."

"Real ray of sunshine, aren't you?" Asuka deadpanned.

"What was that?" The white-haired young woman glared at the female Fujimaru.

"Nothing~" The auburn-haired girl said in a singsong tone.

"A-Anyways, what's our next move?" Ritsuka asked.

"You're asking me?" Olga asked incredulously.

"You are the director, right?" The black-haired boy asked, genuinely confused.

"O-Of course, I am!" The Director of Chaldea retorted with a stutter, pointing her nose into the air. "I'll have you know that I'm quite an accomplished mage!"

Asuka mumbled to herself, "Yet we had to save your sorry butt."

"Fou!" Came the cry of the squirrel-like beast known as Fou. The tiny ball of fluffy white fur hopped off from Mash's shoulder and began to run towards the corner of what looked to be a general store.

"Fou, where are you going?!" Mash called out.

"You think he found something?" Ritsuka pondered.

"Well, don't just stand there, find out!" Olga ordered.

"Uh, yes, Director!" Ritsuka hastily replied, running after Fou with his sister following close behind with a groan.

"Senpai, wait for me!" Mash called out to the Fujimaru twins, swiftly following them and hoping to keep them safe from any nearby danger.

The Demi-Servant dutifully after the last two Masters of Chaldea, watching as the twins turned the corner and she heard a collective gasp from them both. A pit formed in Mash's stomach as she summoned her tower shield in preparation for a battle.

"Senpai, are you-" Mash turned the corner and prepared to attack before pausing when she noticed the twins weren't under attack but rather, they were…bewildered. Needless to say, so was she by what she was seeing.

Fou trotted around a body. A human body. One that still drew breath. "Kyu?" It released a cute noise as it pawed the body.

From what they saw, the figure is male and seemed to be around their age, or possibly a year older. The boy had chin-length dark brown hair, Caucasian skin, boyish facial features, and a small barely noticeable scar on his left cheek. For attire, he seemed to be dressed in a dark blue and gray outfit with a strange belt buckle on his waist that had a small core in the center that was white in color with a red symbol that resembled a fox's face.

"Is he okay?" Asuka asked.

"I…think so." Ritsuka answered, before gently shaking the young man. "Hey, can you hear me? Are you alright? Wake up."

The boy groaned before his eyelids slowly fluttered open, revealing a pair of chocolate brown eyes that seemed rather unfocused. "Where…am I?" He asked weakly. He paused, scrunched up his face in confusion. "Who…am I?"

"Hey, you alright?" Asuka asked, approaching the young man. "What are you doing here?"

"I…I don't know." The young man shook his head. "Everything was black until now. I…don't remember anything either."

"Amnesia?" Ritsuka pondered.

"It is possible, senpai." Mash answered, getting the young man to look at the Demi-Servant.

"What…are you wearing?" The brunette asked, confused.

Before she could answer, Olga arrived, seemingly out of breath. "Honestly, can't you just do anything right? We still have a mission to-" Her words died in her throat when she stared at the amnesiac young man, who stared at her blankly. "Wha-?!"

"Who's that?" The brunette asked, gesturing to the Chaldean Director.

"Um… she's…" Asuka trailed off. "How should I put this? She's-"

"I think the question is, who in the hell are you?!" Olga demanded the amnesiac young man.

"I don't know." He answered, truthfully. "I thought all of you would know."

"Uh, sorry, but…we don't." Ritsuka said, apologetic.

The brunette looked sullen after that, staring at his lap with forlorn. "Oh…that sucks, I guess…" He suddenly winced when his head started to hurt and something in his mind kept going on repeat.

"Hey, what's wrong?" Asuka asked the boy, concerned.

"Do you require aid?" Mash offered.

"I…" The brunette paused when a word kept echoing in his ears. It sounded strange yet for some reason, it felt like it brought joy. "I think…I'm remembering my name…"

"Fou?" The squirrel fox-like creature tilted its head curiously.

"You remember your name?" Ritsuka asked.

"It's…" The young man trailed off, "It's…Ace."

"Ace?" The twins and Mash repeated.

Olga rolled her eyes, "Fine, you know your name. But what I find strange is why a human managed to survive out here."

"Survive? What do you…" Ace gasped when he took stock of his surroundings such as the ruins and the fires. "What the heck? What happened?!"

"Hold on, calm down." Asuka placated the young man. "We just got here ourselves, so we don't know what exactly happened here, either."

"Got here? I am…seriously confused right now. Who are you people?" Ace asked, rubbing his head.

"Ah right, I'm Ritsuka Fujimaru." He introduced. "This is my sister Asuka."

"Hiya!"

"Our kouhai, Mash."

"Pleased to meet you." The Demi-Servant bowed.

"This little guy here is Fou."

"Fou! Fou!"

"And over there is Olga, our…boss."

"THAT'S DIRECTOR TO YOU!" Olga snapped.

Ace looked at the director with a blank expression. "You sure she's your boss and not some loudmouth?"

Olga's face turned red with anger. "H-How dare you speak to me that way!"

"So where exactly are we?" Ace asked the twins and Mash, ignoring the fuming young woman. "I can tell we're in a city but…that's about it."

"Hey! Don't ignore me!"

"We are in a place called Fuyuki City. It is the source of a disturbance that we, of Chaldea, have cataloged as Singularity F." Mash explained.

"Huh…" Ace nodded. "Yeah, that doesn't tell me anything."

"Basically, our job is to find the source of the disturbance, stop it, and make sure that humanity still has a future." Asuka added.

"Wait…you're saying we humans are about to go extinct?" Ace asked with a raised eyebrow.

"In 2016, yes," Olga answered, cutting into the conversation after cooling off.

"That…sounds bad." The brunette grimaced. "Wait…are you sure this isn't the year 2022?"

"Huh/Fou?!" Ritsuka, Asuka, Mash, Fou and Olga looked absolutely gobsmacked.

"I…don't know why but, the year feels like it should be 2022." Ace answered.

"Hold on, 2022?! Did you hit your head or something?!" Olga snapped.

"N-No, no, really. I really do think it's 2022, Year 4 of the Reiwa Era…right?"

"Reiwa?!" Ritsuka, Asuka, Mash, and Olga cried out.

"That's what keeps buzzing around in my head, at least." Ace looked at the group in surprise, "What? Is…that strange or something?"

Olga groaned, feeling a headache on the way. "I'm in desperate need of aspirin right now…"

"Director, I know we still have a mission but maybe we should bring Ace-san with us?" Mash suggested.

"What?" Olga glared with a growl. "We don't have the time to babysit."

"But we can't just leave him here." Ritsuka argued.

"Yeah, besides, he's the first person we've seen so far who isn't…" Asuka hesitated. "Well, dead."

"Mmmmmmmm…" Olga pouted.

"Look, ma'am. I still don't understand what's going on around here." Ace stated. "But, if it's that serious and humanity is about to go extinct, then I'll do whatever I can to help. Within reason, of course, if that's okay with you."

The Animusphere heiress groaned before releasing a sigh of reluctant acceptance, "Fine. He can help. Might as well gain myself another meat shield."

"Uh…" Ace muttered.

"Don't worry, she's always grumpy. It's normal." Asuka whispered to Ace.

"I heard that!" Olga snapped.

"Anyways, we should probably get a move on." Ritsuka said, holding his hand out to Ace, who accepted the gesture when the male Fujimaru twin pulled him up to his feet and the group began walking. "We still need to find out where the source of the Singularity is coming from."

"Singularity?" Ace parroted.

"It's basically a point in history that messed up the timeline. We take care of it, and the whole timeline fixes itself."

"Huh, I guess that makes sense." The brunette teen remarked, rubbing his chin. "So, what exactly could be the cause?"

"We believe it to be an omnipotent wish-granting device called the Holy Grail." Olga answered.

"Holy Grail? You mean the chalice of Arthurian legend that was supposedly used at the Last Supper, then later caught the blood of Jesus Christ at his crucifixion and then entrusted to Joseph of Arimathea?" Ace pondered.

Everyone stared at the brunette in shock, making him feel a bit self-conscious from all the attention.

"I'm…slowly remembering some stuff." Ace answered, sheepishly.

Mash quickly collected herself and explained, "Not exactly. While it is called the Holy Grail. It is actually a construct that allows one access to the Swirl of the Root."

"The…Root…"

"Supposedly it is a place that stores and archives information of all possibilities and events, past, present, and future, of the world. A well of knowledge, if you will."

"Oh, so it's like a big library then." Ace nodded. "That makes sense."

Olga sighed, "That's as clear of an example as that can be."

Suddenly, Mash froze, feeling a sensation.

"Mash, what's wrong?" The boy, Ritsuka asked, concerned.

"Senpai… I sense something." The lilac-haired girl had a grimace on her face. "This sensation… it's a Servant!"

After running for a few minutes, the party managed to come upon a waterfront that would've been nice to look at…if it weren't for the dozens of stone statues that resembled people; all of whom looked like they were fleeing for their lives with expressions of fear on their faces.

"That…is extremely disturbing." Ace stated.

"These people…" Asuka frowned in conflict. "What exactly happened here?"

"It should be obvious. These people fell prey to a Servant." Olga told the two Masters while Mash kept a watchful vigil for any enemies.

"But…why would they do this?" Ritsuka pondered, looking at each of the statues with horror.

"It really looks post-apocalyptic…" Ace grimaced, also examining the statues. "It's like those people in Pompeii when Mt. Vesuvius erupted."

"We need to keep moving." Olga said with a grimace. "We can't do anything for them."

The others knew the Director was right, but it still didn't feel great to do so. However, just as they were about to leave, they were suddenly stopped by what looked to be a wall of chains.

"Are these…chains?" Asuka pondered, reaching out towards them.

"No, don't touch it!" Olga cried out.

Asuka jumped from the order and looked at the white-haired young woman before the chains suddenly moved of their own free will, seeking to ensnare the auburn-haired girl. At least, until Ace grabbed Asuka and pulled her back.

"Asuka!" Ritsuka cried out, checking his twin sister to see if she was okay.

"What the hell was that?" Ace questioned, feeling the hairs on the back of his neck stand up.

"Too bad." Soft giggling laced with a seductive allure yet tinged with malice filled the air. "The fresh prey got away."

Suddenly, in a small burst of purple light, a new figure appeared on the riverside hill overlooking the party.

Garbed in a black cloak suited for a grim reaper yet opened to show off a risqué black toga that revealed a generous amount of cleavage, her arms covered by black silk gloves, her legs bare save for the intricate red tattoos on her thighs, and armored heeled boots. In her right hand, she wielded a scythe. The woman possessed rather long light purple hair and her eyes were a sickly yellow color with the pupils square shaped.

"Who is that?" Ace questioned.

"A Servant." Olga answered.

"A what?" The brunette looked at the Director in confusion, but Olga didn't deign to answer at the moment.

"An Unknown Servant and two Unknown Masters." The dark-garbed woman stated. A seductive yet malicious smile present on her face. She made a pleasant noise, "How young and fresh…" She said, hungrily.

Mash quickly stood in front of the twins, Olga, and Ace. "I don't see her Master…" She said, grimly. Tower shield at the ready.

"This world has already gone mad." Olga pointed out. "I'm not surprised to see a Servant without a Master."

The female Servant approached a stone statue of what looked to be a teenage boy with seaweed-like hair and ran a clawed hand over the statue's horrified face.

Ace narrowed his eyes at the woman, "Did you do this?" He demanded, referring to all the people turned to stone.

"What's it to you, boy?" The woman inquired.

"Answer the question!" Ace demanded. "It's a simple yes or no!"

The Servant stared at the brunette in mild surprise before her eyes lingered on the belt around his waist which caused her pupils to dilate. "That belt…" She mumbled before smirking. "I see, so you are the one that they warned me about."

"What?" Ace blinked in surprise, confused by what the Servant was talking about.

"Belt?" Asuka was also confused.

"Fou! Fou!" The squirrel-like fox pointed at Ace's waist with its paw.

"Huh? You mean that weird belt that Ace is wearing?" Ritsuka looked at the buckle and didn't really see what made it so special. It almost looked kinda like a toy.

"They warned me that if I were to ever encounter you," The dark-garbed woman spoke, getting the group's attention. "I need to make sure that you die. Luckily, they provided me with ample assistance for one like you." She brought her fingers up to her lips and released an echoing whistle.

Silence loomed in the area for a few moments. Before…the sound of "Jya, jya, jya" echoed in the air.

"What's that sound?" Olga asked.

Ace listened to it before he felt another headache, causing him to grit his teeth in pain. "Urgh! That…noise. I…I know it."

"Hey, are you okay?" Ritsuka asked.

"Fou! Fou! Fou!" The squirrel fox pointed with its paw as a group of strange monsters approached them. For one, they were dressed with black bodysuits with white and purple lines. It had shoulder armor with a texture that's similar to that of bone and its shoes were curled at the tip. But the head was a different story altogether, as it looked like a pawn chess piece with a leather-like protrusion in front, shaped like a flattened elephant's trunk.

"What are those things!?" Asuka pondered in fear, hiding behind her brother.

"J-Jyamato…" Ace spoke the name of the creatures with gritted teeth.

"Jyamato?" Olga parroted.

"Yeah…they're bad news. Enough said." Ace answered. "I don't think you're ready to face them yet."

"None of you are prepared to face my new pets." The woman stated. Her gaze went from Ace to Mash, who continued to stand ready for a fight. "Is this your first time fighting as a Servant?" She asked but received no answer, yet she could tell that the lilac-haired girl was inexperienced in combat. "Then, as your senpai, I'll teach you." She twirls her scythe with a flourish before brandishing it for conflict. "Be careful of what you say and do. Once the word "fight" passes your lips, it has already begun."

Without warning, the dark-garbed Servant lunges towards Mash while the Jamato advances upon the humans, beginning what is surely a dangerous battle.

"Move, now!" Ace shouted.

Mash used her shield to contend with the Lancer, blocking a few strikes thanks to the enormity of her shield. Meanwhile, the four humans fled from the Jyamato that were chasing after them. Olga brought up her left hand like a gun and fired a Gandr curse at the Jyamato. However, while her attack struck true and the Jyamato hunched backwards, it suddenly straightened itself up.

"Impossible!" Olga gasped.

"Are these things unbeatable?!" Asuka panicked.

Ace grimaced. He knew that the Jyamato weren't invincible but for the life of him, he can't remember what could actually beat them. "Just keep avoiding them! Maybe if Mash beats that woman, the Jyamato will give up."

Just as he said this, Mash lands on her feet in front of the group after pushing back Lancer with her shield, surprising the other teens.

"Mash!" Ritsuka and Asuka cried out at the same time.

"Master, I will not be able to beat her. I recommend all of you to flee while I hold them here." Mash told the group with grim acceptance.

"But Mash…" Asuka hesitated as she noticed the approaching Jyamato, now wielding kukri knives in their hands.

Ace gritted his teeth in frustration. 'If this keeps up, we'll all…'

Do you wish to save them?

The brunette's eyes widened when he heard a voice…and noticed the others frozen in place. "What the…? Guys, what's wrong?"

Do you wish to save them?

"Who's there?!" Ace demanded, looking around wildly. "Show yourself!"

His demand is met by…a white fox?

"What the…" Ace trailed off in confusion before flinching when the Fox approached him…with a strange device held in its mouth. Inside of its mouth, looked to be some sort of buckle attachment, almost shaped like the revolving chamber of a gun along with a trigger. "This is…"

Become humanity's last hope.

"Huh?"

*VROOOOOOOOOOM!*

Ace heard the unexpected sound from behind and quickly ducked, watching as a blazing object flew over his head until it turned and went right up to him. The flames ceased to reveal another buckle attachment except this one looked like a motorcycle throttle with a red metal cowling that looked as if it could open.

"These buckles…" Ace muttered, staring at the devices in his hands before his gaze returned to the fox. "Can I…really save them?"

If that is what you desire, then you must fight for it.

"My desire…" The brown-haired young man mumbled, reminiscing over the phrase even as the white fox disappeared, and time had resumed. "Yes, my desire…"

"Huh? Ace-kun?" Asuka looked at the brunette before noticing the devices in his hands. "What the-? Where did you get those?"

Ace didn't answer. Instead, his eyes seemed to burn with a lit flame while a smirk appeared on his face. "I really should thank you, Lady Servant." He said, addressing Lancer as she stood behind her small army of Jyamato. "You've helped me remember a small part of who I am."

"Hm? What do you mean?" the Servant inquired, before noticing the buckle-like attachments. "It can't be…! How did you-!"

Ace didn't answer as he raised the gun-like buckle in the air, his smirk still present. "The Holy Grail War is supposedly a tournament between Masters and Servants. However… The winner in the end is me!" He said before inserting the buckle on the right side of his belt.

SET

A high pulsing noise echoed out as a holographic logo of the revolver chamber appeared and the word 'MAGNUM' followed. He then pivoted his body so that the Servant saw a side profile of him, then moved his arm in an arc motion before sticking out his arm, his hand in a canine gesture before snapping his fingers.

"Henshin!"

He starts by rotating the revolving chamber then finishes by pulling the red trigger. Multiple 'bullets' shot out of the buckle which hit the logo, shattering it before the debris seemingly flew towards him, but then the debris somehow crumbled and rearranged itself into forming…armor?!

A ring appeared around Ace before splitting into two rings that went up and down his body, engulfed by data particles until it formed a full bodysuit that was black in color with a few pieces of black padded armor as well as a silver lining that ran from his lower right hip to his upper left rib side. The only thing with added color is a white *mask* in the shape of a fox's head with red outlines and hollow "ears" but with dim compound eyes.

The set of white armor that formed from the 'debris' had a gun-based look and had appeared on the right side. Then a crank-like device appeared, holding the armor before sliding it onto Ace and giving him a brand-new appearance.

He now had pure white armor covering his chest with the chest piece in the same fashion as a revolving ammo chamber, white shoulder guards with red lining that resembled the hammer of a revolver, armored gauntlets with what look like retractable gun barrels, a white scarf with a red tip at the end like a fox tail, and the lower half of the helmet now had a white outline with red "trigger" markings as the eyes went from dim gray to a deep vibrant orange. He also held what looked to be a high-tech magnum hand cannon colored white, red, and black yet the name of the weapon entered Ace's memory with ease: Magnum Shooter 40X.

MAGNUM

READY? FIGHT!

Ritsuka, Asuka, Olga, Mash, and Fou all stared at the armored Ace in pure shock, gob smacked at the fact that their new friend changed into…something! Whatever he was supposed to be!

"Is…is that…" Asuka began.

"He's a Kamen Rider!" Ritsuka exclaimed.

"A Kamen what?" Olga looked at the twins in confusion.

["DID SOMEONE SAY KAMEN RIDER?!"]

Everyone looked surprised as Ritsuka's watch suddenly shot out a holographic image of a person. He was a young man in his late 20's, with messy peach hair, tied up in a ponytail and wearing a lab coat over his aqua-green shirt, beige dress pants and brown shoes.

"Dr. Romani, what the hell are you-" Olga got out.

["OH MY GOD, IT IS! A REAL KAMEN RIDER!"] The now named Romani exclaimed happily with sparkles in his eyes, weirding out Olga. What was wrong with him?!

The Kamen Rider shook his head before leveling a featureless glare at the Servant and the Jyamato.

"Now, here comes the highlight!" The fox Rider said, aiming his Magnum Shooter 40X at his foes in a rather dramatic fashion.

Lancer snarled, "So it's true. You are a Rider."

"Indeed. And I even remembered my name in this form. I am Geats." He said, spinning his hand cannon with ease. "Kamen Rider Geats."

"Kamen Rider Geats?" Mash repeated.

"Ritsuka, explain to me what the hell Ace is!" Olga demanded.

"Oh, uh, how do I explain that…" Ritsuka rubbed the back of his head, sheepishly. "Um, a Kamen Rider is…like a superhero that's famous in Japan. They basically fight monsters that no ordinary humans can fight and are well-known for riding motorcycles and their iconic masks."

"So why is it that I've never heard of this before?" Olga questioned.

"Because Kamen Riders are only native to Japan. Duh." Asuka pointed out, dryly. "Plus, the Americans tried doing their version and they botched it sooooooo bad."

"I mean, they didn't do so bad with Ryuki's adaptation. I kinda liked that one better than our own, to be honest." Ritsuka admitted.

"Traitor…" Asuka muttered.

"Hey!"

"So, from my understanding, you mean to tell me…that these Kamen Riders…are fictional and show up on a Saturday like some cartoon?" Olga growled irritably.

The twins look at each other then back at their boss, "Pretty much, yeah." They answered in unison.

Mash looked at Geats with awe, but her gaze also lingered on the "fox ears" atop of the Rider's head. "Kamen…Rider…" She repeated the words her senpai used.

"Hmph, it doesn't matter what you call yourself. In the end, you're still just a human." Lancer spat before looking at her Jyamato minions. "What are you fools waiting for? Destroy him!"

However, the Jyamatos didn't move an inch.

"Looks like they know when they lost a battle." Ace smirked behind his helmet. "Or maybe, they just don't respect you."

Lancer snarled before using her scythe to cut off a Jyamato's head, causing the others to flinch in collective fear. "I will not say it again: Destroy him or I destroy you!" She warned her minions.

The Jyamato all looked at each other, then back at Geats, before brandishing their kukri knives and charging in.

"Finally. Now I can begin the highlight." Geats said before aiming the Magnum Shooter 40X and pulling the trigger as the hand cannon rapidly fired out bullets that struck against the Jyamato that were a few feet away from him. "Oh, hand-to-hand now? Alright then." The first Jyamato that tried to take a swing at him with its kukri was met with the fox Rider's boot to the side of its head, knocking it to the ground and giving Geats the chance to bring up the Magnum Shooter behind him, firing a bullet that struck two Jyamato at the same time.

"This is impossible!" Olga gawked.

"Riders are known to do the impossible, no matter how ludicrous it is." Asuka pointed out.

Geats parried away a kukri with his gun then kicked the Jyamato attacking him in the chest, knocking it into a trio of its kin before the Rider pulled the hammer of his weapon back.

BULLET CHARGE

"Take this!" Geats exclaimed, aiming at the Jyamato before pulling the trigger. What followed after were several rapid shots that struck his enemies, causing them to explode in a fiery blaze. "Oooh, nice fireworks." He commented, nonchalantly.

Lancer watched how the Jyamato were easily defeated by the Rider and growled in frustration. "Damn you…! Fine! I'll kill you and that little girl myself!"

"You're welcome to try. Your defeat is gonna be the main highlight of the day."

"Grrrrrrrr… have at you!" Lancer shrieked as she charged in and swung her scythe.

"Hup," Geats casually leaned back, avoiding the curved sickle edge that was getting dangerously close to his face. "Nope. Missed me. Too slow." He continues to dodge the attacks and even manages to slip behind the Servant by sliding between her legs. "Oh, how daring." He commented when he glanced up behind the compound eyes of his helmet.

"Where do you think you're looking, pervert?!" Lancer snarled, attempting to slice him from down under, only to miss again.

"Can't really fault a guy for being curious. Besides, I'm not the one running around and going commando." Geats teased his opponent while shouldering the Magnum Shooter. "Oi, Mash, care to give me a hand?"

"H-Huh?!" Mash seemingly snapped out of it, if only because of being in awe of Geats' fighting prowess. "R-Right, I'm coming!" She said, before rushing over to him.

Lancer scoffed. "Even with the girl's help, it will not save you! My weapon is the Lance of Immortal Killing. Any wound this lance delivers cannot be healed by any means!"

Olga gasped at the identity of the weapon that Lancer disclosed to everyone present. "That means-"

"It won't really mean much. We just have to avoid getting hit by it." Geats remarked, casually.

The dark-garbed woman scoffed, "In that case…" She runs her hands through her long hair before flicking her arms out and sending out snakes which turned into more chains that circled around the Rider, Demi-Servant, and the three humans watching the battle. "I'll simply entangle you all with my hair. Then, I'll take my time dealing with you, one-by-one."

Mash readied her shield for an incoming attack while Geats slowly moved his unattended hand to a holder on his belt where the red buckle rested.

"You've got guts." A new voice cut in. "A little girl is still a little girl, but you seem pretty strong. Plus, I rather like the little fox playing around with his food. That's why I can't leave you like this."

"Who are you?" Lancer demanded, sensing the presence of a Servant.

"Who? Look at me and you'll know…" The voice said, good-naturedly. "...old friend." A burst of blue light emerged from further away to reveal a new Servant.

This time it was a man in a pale blue robe wielding an elaborate wooden staff. He pulled his hood down to reveal short top blue hair with a pair of long streaks of hair going past his shoulders, his eyes opened to reveal a pair of blood red orbs glinting with amusement and he was sporting a rather bloodthirsty smile.

Lancer gritted her teeth at the sight of the newcomer. "You…" She snarled. "Caster!"

Geats inclined a hidden brow of interest. 'Caster, huh?' He said mentally.

"Why do you side with these wanderers?" Lancer questioned the mage.

Caster gave the woman a look as if she had asked him a rather stupid question. "Because it's better than being on your side, of course!" He declared, waving his hand as several Gaelic runes appeared in the air then transformed into literal fireballs that were shot right at Lancer. The spearwoman grunted in annoyance as she kicks off from her chains to avoid the majority of the fireballs that struck her original position, causing a briefly large explosion.

The Chaldea group and Geats watch as Caster casually stands in front of them against Lancer. "I'm a Caster Servant. For a certain reason, I consider her an enemy." He explained, referring to the dark-garbed Servant. "The enemy of my enemy is not necessarily my ally, but for now, you can trust me. Get in position, young lady, little fox. Skills aside, your courage is second to none."

"Thank you!" Mash replied, returning to her defensive stance.

"Not sure I like being referred to as a little fox, but I'll let it slide this once." Geats commented with a hand on his hip.

"Kids!" Caster called out to the Fujimaru twins. "Are you two Masters? Then I'll leave it to you for the commands."

"But…" Ritsuka tried to explain but Caster cut him off.

"If you call yourself a man, steel yourself!" The blue-haired spellcaster stated. "It'd be a temporary contract, but out of regard for that brave young lady and the little fox, I'll become your Servant."

"I thought I said, I didn't like to be referred to as "little fox"." Geats remarked but Caster ignored him.

Lancer looked at her assembled foes with a frown before smirking rather confidently. "That's fine with me. It means I can kill you earlier than planned." She stands from her kneeling posture. "I'll take you while you're still flesh and blood."

Geats hummed in response, "Well, then I guess I'll have to stop playing around." The Rider brought up the red buckle that he had been reaching for then slid it on the left side of his Driver.

SET

This time, a holographic logo with the word "BOOST" appeared on the left side of Geats with an image of a motorcycle speedometer blazing with heat.

Quickly, he repeated what he had done with the Magnum Buckle then he grabbed the throttle of the red buckle and twisted it once then twice.

*VROOOOOOOOOOM!* *VROOOOOOOOOOM!*

DUAL ON!

The ring appeared once more but now it formed a set of red armored leggings with exhaust pipes on the side until the crank arm reeled in the leggings to the Rider. Once formed, Geats now had bright red armored knee guards and anklets with exhaust pipes on the ankles.

GET READY FOR BOOST & MAGNUM!

READY? FIGHT!

Geats brought up the Magnum Shooter, "Well then, time to begin the final highlight." He said with a hidden smirk behind his helmet.

"Oh? That's a pretty interesting set of armor there, fox." Caster complimented.

"Geats-senpai, how many forms do you have?" Mash looked at the Kamen Rider in surprise.

"Hm, no idea, but I feel like I have a lot." The fox Rider shrugged. "But let's focus on her, for now."

"Hmph, it does not matter what you look like." Lancer scoffed with a wicked smirk. "You'll die like everything else."

"We'll see." Geats said, playfully.

Lancer growled before using her innate ability to control chains to send out two coiled ones towards Caster and Geats, forcing both Rider and Servant to leap in the air to avoid the attacks. However, the chains were not finished yet and followed after its prey. Caster nimbly dodged the chains with gritted teeth while Geats stepped off and even used the boost exhausts to quickly dash away from the chains. Lancer took this opportunity to make an attack on Caster, delivering an overhead slash attack but the spellcaster used his staff to block her yet the force sent him to the ground. Geats brought up his Magnum Shooter and fired at the enemy Servant, forcing her to twirl her lance in order to deflect the bullets yet a few managed to scratch the woman.

"Urk! How? How can this human be able to harm me?" Lancer pondered, looking at the scratches inflicted on her from the Magnum Shooter's bullets.

Geats landed on his feet and did a gesture involving his middle and ring fingers meeting his thumb while his index and pinkie were raised up; the gesture resembling a canine. "Anything is possible, so long as I desire it. And I desire to defeat you."

The Servant of the Lance snarled at the Kamen Rider and prepared to attack him until her danger sense warned her to move, avoiding a barrage of fireballs from Caster. "Oi, oi, remember that you still have a prior engagement with me." He teased her.

Lancer gave her fellow Servant a bloodthirsty grin before dashing towards the druid, forcing him to avoid being cut by the Immortal Killing Lance. She didn't even care if her missing attacks struck the statues around them. "It's all you can do just to run away! It seems you don't even have time to cast a spell, right?" Caster rolled away from another blow, landing in a crouch as Lancer advanced upon him. "This is what you get for opening your big mouth. This is what happens when you express your true intentions." She brings up her lance in anticipation of finishing off the spellcaster.

However, Caster smirked, shocking Lancer before the man called out, "Young lady!" In a split second, Mash appeared in front of the Servant of Spells, tower shield blocking the sickle as the force sent Lancer back a few feet. Caster stood back up to his feet and stood beside Mash, "I don't need to chant a spell to use Runes. Go back to school, you dimwit!" He said, condescendingly before throwing out his left hand.

Lancer gasped before looking down at her feet as a rune appeared then exploded, engulfing the dark-garbed woman in powerful flames, causing her to cry out in pain. Once the flames vanished, Lancer could barely stand up on her feet, having to brace herself using her sickle as support. Burns and scorch marks marred her body and clothing.

"It's your turn now, little fox." Caster called out, shocking Lancer before she heard a noise behind her that sounded like the cry of an animal.

"Thought I said not to call me little fox." Geats commented as he sent his Magnum Shooter away and got in a stance. He spins the revolving chamber and pulls the trigger on the Magnum Buckle before revving the throttle on the Boost Buckle twice as flames erupted from the exhaust engine on the buckle.

BOOST TIME!

The sound of a screeching noise echoed as a red motorcycle with no driver suddenly turned the corner, coming towards Ace. The red motorcycle, much to everyone's surprise, changed form into a…red mechanical fox?!

"There you are." Ace grinned behind his mask.

*WREEEEW! WREEEEW!*

"I know, I know. Let's save the reunion for later. We still have a finisher to do, after all." Geats told the mechanical fox. Suddenly, the exhaust pipes on his ankles ignited like booster rockets, propelling the Kamen Rider into the air while the fox followed after him by quite literally running on air. Once the duo were high enough, Geats landed on the fox's back and grabbed the throttle of the Boost Buckle before revving it one last time.

MAGNUM-BOOST: GRAND VICTORY!

The mechanical fox began to run, propelled by its boosters before turning into flames that surrounded the Kamen Rider, who descended towards Lancer with his right foot out in a flying kick maneuver. "HYAH!" He cried out as an image of the mechanical fox appeared beside him along with Geats' symbol emerging from his kicking foot as he struck Lancer dead-on. The woman cried out as Geats appeared behind her in a crouch. The Servant looked at the sky for what is likely her last sight before being engulfed in a large explosion complete with dark purple particles as the mechanical fox appeared behind Geats, releasing another mechanical cry.

"Whew…" Caster whistled in amazement. "Now there's something you don't see every day."

Geats stood up and looked at the mechanical fox as it approached him then sat down dutifully like a guard dog. "Thanks for the assistance, partner. See you later." He told the fox before removing the Magnum and Boost Buckles from his Driver, canceling his transformation and reverting him back to normal.

"Ace-senpai!" Mash called out, approaching the young man. "Are you alright, senpai?"

"I should be asking you that." Ace replied. "But I thank you for your concern, all the same."

"Gotta say, you two," Caster spoke, grabbing the attention of the Rider and Dem-Servant. "You've really shown that you've got guts."

Mash bowed politely towards the Servant, "Thank you." She fixed her posture. "You saved us when we were in danger."

"Well, good work." Caster praised the Shielder, placing an arm over her shoulder. "We were saved because of your support. Don't worry about it." He said with a wink while lightly fondling the confused girl's exposed shoulder.

"Hey, old man. Mind taking your hands off her?" Ace deadpanned. Fou, having hidden himself within Mash's shield, appeared on the girl's shoulder and hissed at Caster as if warning him not to touch Mash like that again. This only caused the blue-haired man to laugh out loud.

"You have a fine body." He commented, shocking the teens and causing Mash to feel a bit self-conscious about herself.

"That's one sexual-harassing old pervert." Olga said, dryly.

In a split second, Romani's hologram appeared beside Olga, ["For now, let's ask him about the situation. It seems that he's a sane Heroic Spirit."]

Caster took notice of the hologram and could feel the prana from it. "Oh! Is that some means of communication through Magecraft?"

Romani gave the Servant a polite bow, ["It's a pleasure to meet you. Heroic Spirit, I don't know where you hail from, but it's an honor-"]

Caster interjected in a bored manner, "There's no need to be so florid." He dismissed the likely brown-nosing. "Just state your business quickly. You're good at that, right, weakling-man?"

Romani gaped in shock at the disrespect from the Servant. ["W-Weakling…"] He said, weakly.

Ace ignored all of that. Instead, he focused on the chains disappearing after Lancer's death. However, he didn't care about what happened to the Servant. His thoughts drifted to what she had said before.

"She knew I was a Kamen Rider." Ace said to himself. "But how? Who told her? And why me?"

Deep within the former remnants of Ryuudou Temple, the warrior in control of the Greater Grail stood patiently while the world burned around them.

"Are you not going to face them, Saber? After all, they have come to take the Grail from you." A disembodied voice spoke to the warrior.

"There is no need. They will come to this place eventually." The warrior remarked, remaining where they stood.

"Hm, I see. I suppose that's fair. But I should warn you, the fox is among them."

Pale yellow eyes opened up with a cold stare. "Oh? Well…this might prove to be worthwhile."

A dark aura began to form from the sword currently embedded in stone, the warrior slowly grabbing it and pulling it from the ground.

"A chance to battle these foreign heroes. This…Kamen Rider Geats." The warrior said.

"I love that optimism of yours but I warn you all the same. Do not underestimate the Rider. Lancer learned that the hard way."

"Hmph…I'll be the judge of that. Whether or not he is a worthy foe."

"There will be others. Pray that these foreigners don't multiply like the ants they are."

"It doesn't matter. They will fall before my blade either way." Saber remarked, a pulsating glow emerging from the pit behind them.

In another part of Singularity F, a man was walking alone through the ruins. His body was covered by a cloak as his eyes were a bright red and filled with malice. The times his cloak blew in the wind, it would reveal a buckle similar to Geats, except the centerpiece was purple instead of white.

"I will survive no matter what…" the man said to himself. "And I will make sure… that all Kamen Riders get destroyed by my hands."

In his right hand was a buckle, completely purple resembling a ribcage with red filling in the gaps.

A/N: And that shall be the end of the first chapter.

KRD: Gotta admit, this is a crossover I never considered at all. Well done.

SR: Man, it's been AGES since we've collaborated on something.

GKC: Well, that's also because I'm the one that's got a far more active imagination. This brain has never-ending ideas. And with the end of Geats, plus the setting revolving around it, this particular Rider seemed perfect to crossover with FGO. Wait…HOW THE HELL DID YOU TWO GET HERE?!

KRD: Uh…we thought it would be fun, so~ we joined without telling ya. Also, about time you finally noticed us.

SR: Yeah!

GKC: Oh. I guess you guys always felt like background characters to me. My bad.

SR: Oof!

KRD: Oi! Just because we help you out, doesn't make us your minions!

GKC: I mean, to be fair, I came up with the idea and I also happen to be the author.

SR: He's got us there.

KRD: Grr…fine. I'll let it slide…for now. Speaking of collaborations though, we got something to say about Remnant's Climax Heroes… we, uh… we got to rehash it. It sucks so much, being in the middle of writing something great, only to get stopped in our tracks and start over. My PTSD of constantly rehashing Kamen Rider GX still haunts me!

GKC: That, and I looked back on the story, it…is not following a proper Kamen Rider formula.

SR: And that's why we're taking a look to see how we can improve it!

KRD: We're so sorry that you have to wait for so long though… I know you guys are looking forward to reading more, but… arrrrrgh, THIS SUCKS!

GKC: Uh, you're not the one who has to read all the angry reviews and PMs from fans, man. But they should be happy, we can fix up some stuff and even do a few changes that will make the Aura Kamen Riders more effective as characters.

KRD: Yeah, I…guess so. Sorry… :/

Anyways, enough about that. I still have to finish the author notes.

Review and comment on this story. Love it, hate it, but just know that you've read it.

Peace out, everyone!

KRD: And for old time's sake, ROLL THE PREVIEW CLIP!

Huh!? Wait, don't-

PREVIEW

Narrator: NEXT TIME! On Fate/Geats Order!

Romani: I can't believe it! A real Kamen Rider!

Ace: I still have no memory of my past nor why I became a Rider.

Man: So you're still alive…Geats.

Caster: Our mutual foe is Saber and their guard dog, Archer.

Archer: Oh? I don't remember becoming anyone's disciple.

NEXT TIME: Singularity F: Battle for the Grail! The Undead Bull

Man: This time, I will beat you, Geats!

ZOMBIE!