I don't own Fate/Stay Night or Kamen Rider and they belong to their respected owners.

Berserker was about to crush only for Shirou to push out of the way by an unknown figure.

"Ugh!" Shirou grunted as he roughly rolled down the road. "Ow."

"You okay?" Asked a new voice.

"Yeah, thanks uh…" Shirou looks up to see an orange and black figure. "Uh, who are you?"

The unknown person stood up and helped Shirou up.

"Kamen Rider Ghost, Tou-san," Ghost introduced himself.

"Eh?" Shirou gives Ghost a blank stare while tilting his head.

"Emiya-kun, what the hell is going on?" Rin questioned him.

"Don't worry Kaa-san, all things will be explained soon," Ghost said.

"Eeeh?!" Rin shouted as she was shocked as well.

"I don't know who you are but now that you got in the way you will have to die as well," Illya said. "Berserker kill him!"

Berserker brought both of his fists to crush Ghost leaving a big boom as he destroyed the sidewalk where he was standing. When he lifted up his fists, Ghost was not there.

"I did say my name is Ghost, right?" Ghost said behind Berserker. "You know my parents told stories about the Holy Grail War, but I thought it was all made up. I mean fighting to the death with historic spirits to fight.

"And you know what I kinda do the same," Ghost then brought on a brown eye looking device. "Luckily I got this Eyecon before I met you guys," said Ghost, then he opened his belt and took out the Eyecon end and replaced it with the bronze color one then he pulled the belts lever.

KAIGAN! BILLY THE KID!

Ghost's black and orange parka disappeared while a brown parka with a cowboy hat came out of his belt then floated around before attaching itself to Ghost.

HYAKUPATSU! HYAKUCHU! ZYUKUN! BAKYUN!

Billy The Kid Parka donned onto him as his armor was formed. While he now looks like a cowboy, the faceplate shows a six-shooter revolver, firing and was brown. Ghost quickly withdrew two dual wield guns with one of the rifles looking like a clock.

"What the…" Shirou looks shocked.

All the Masters and Servants were shocked by Ghost transformation and gaining the parka of Billy the Kid.

"What is this?" Rin asked.

"I'm using the soul of Billy the Kid and he granted me his powers and skills when I wore the Parka," Ghost said as he began to fire at Berserker who covered himself. "Don't worry guys I can handle this." Ghost began to dodge all of Berserker's attacks.

Ghost then combines the two pistols into a rifle. He lowers the rifle to his belt's eye and scans it with the hilt of the rifle.

DAI KAIGAN!

Ghost raised his rifle at the giant brute looking at the energy construct of a scope lens, "Don't worry big guy this won't kill you it's just gonna hurt."

GAN GAN MINA! GAN GAN MINA!

Berserker raised his fist again to squash the ghost while Ghost pressed the trigger on his rifle.

OMEGA IMPACT!

Once the clock hands point at the muzzle of the gun barrels and the energy is fully charged, Ghost fires a powerful shotgun blast which hits Berserker straight at his stomach sending him back and giving him a large explosion.

"Berserker!" Illya cried out as she ran towards her Servant. "You pay for this!" Illya glared at them as she and her Servant escaped.

"Phew, now that was exhausting," Ghost says as he turns around to see Rin up in his face with a glare.

"Who are you? How did you do that? Are you a mage? And why do you call me mom and him dad?!" Rin pointed at Shirou.

Ghost opened his Belt to remove the Eyecon having his armored vanish showing his true self. He was a young man with auburn hair that was in a medium length hairstyle and with aqua eyes.

"My name is Emiya Hikaru, and I am your son from the future and the past is in danger," Hikaru said.

"Danger? What are you talking about?" Saber asked.

"Deities called the Gammaizers," Hikaru answered. "They came from the Gamma World which I'll explain to you later but they think humans are too chaotic and would purify us into their own mirror image."

"So why did they come here to the past?" Shirou asked.

"It's because they heard about the Holy Grail War didn't they," Archer says.

"Yeah," Hikaru nodded. "I don't know why they chose this year but the future is in danger."

"How can we help?" Shirou gives Hikaru a determined look.

Hikaru smiles as he sees his father's determined look. "What I need help with is locating the Eyecons." Hikaru shows Billy the Kid Eyecon.

"And what are these?" Rin asked.

"They're Eyecons that have souls of the legendary figures," Hikaru answered. "And if you collect all 15 of them you can make a wish."

"A wish?" Rin eyes go wide.

"Yeah, apparently it grants any wish," Hikaru says.

"So, it's similar to the Holy Grail," Rin implied.

"I guess? I don't know much about the Holy Grail, my parents don't really talk about it," Hikaru said. "Anyway, can we go somewhere else it's getting a bit cold outside."

"Yeah, we can get to my place," Shirou says as he led them to his home.

~/~

One and a half months later:

"Gah!" Shirou and Hikaru screamed as they were attacked by Archer who happened to be a future version of Shirou.

Shirou de-henshin from his Zero Ghost suit and looked down to see his Ghost Driver and Eyecon busted. While Hikaru was still in his Toucon Boost form.

"You should give up!" Archer says.

"You get Kaa-san to safety!" Hikaru told his father. "I handle it from here."

"No! I won't leave you alone to face him!" Shirou says. "Remember what you taught me, if I overcome power, I can overcome anything."

Hikaru nodded.

"I was wondering if I should be a Hero of Justice but I realize that I don't need to be one," Shirou says. "I let Kiritsugu ideals get to me and never realize how sad and lonely he was. But after meeting you and learning what kind of future I will have." Shirou smiled.

"Tou-san…" Hikaru mumbles.

"My true goal is to create a world so I laugh with my friends and family to walk the path I believe in," Shirou says as he looks at Archer. "I will have an unwavering heart to bond with others! Because even if I fall, my soul will live one!"

Archer glared as he was about to walk towards them as he was attacked by the 15 Damashiis.

"Everyone… what are you doing here?!" Hikaru asked.

They see the 14 Damashiis formed an oval with Musashi, holding the giant Eyecon, at the center.

"Shirou! We heard your words!" Musashi says. "Inherit the legacy of our souls!"

And with that, he went into the giant Eyecon. Followed by the others entering, the Eyecon glowed into a golden color and fell into Shirou's hands.

"Everyone's souls…?" He murmured.

Shirou put the Eyecon on his waist. The Eyecon then spewed out a belt strap around him.

GRATEFUL!

He pressed the button and waited.

GAT~CHIRIMI~NA! KOTCHINIKINA! GAT~CHIRIMI~NA! KOTCHINIKINA!

Shirou pressed the button again, and let the Damashiis do the rest.

ZEN-KAIGAN! KENGOU, HAKKEN KYOSHOU NI OHSAMA, SAMURAI, BOUZU NI SNIPER! DAI~ HEN~GE~!

Shirou's new black transient armor was formed. It was mostly black, with golden outlines, and was a bit bulky as all 15 Damashiis flew out of the belt Eyecon and attached themselves on to the various armor parts that materialized on Shirou. As the Eyecon's symbols form into the armor plating onto his suit with Musashi for the breastplate, Edison and Newton for the left and right shoulder pads, Nobunaga and Tutankhamen's faceplate on his right forearm, while Beethoven and Billy the Kid onto the left. Next, Houdini and Benkei on his waist, Himiko and Goemon's faces as knee pads, Robin Hood and Sanzo on the right shin, while Ryoma and the Grimm's faceplate on his left. Shirou gains a new faceplate and helmet, the orange cover is black, while the eyes were golden. His helmet gaining several ornaments, resembling a king with a golden horn on top with the side of his helmet having different horns and decorations found on the various Parka Ghosts. In the center of the Eyecon Driver G, it showed not only the symbols of all of the Damashii was fused with but also the very same faceplate that was on him right now. Shirou became Kamen Rider Ghost Grateful.

"Nani?!" Archer looked on in shock.

"Shirou…" Saber looked at her Master with awe.

"He gained all the trust of the luminaries and received their power," Rin says as she looks at Shirou.

"Hikaru, let's show him why our life is bright," Shirou says.

"Hai, Tou-san!" Hikaru nodded as they both charged at Archer.

Shirou wields Gun Gun Saber while Hikaru uses Sunglasseslasher and they begin clashing with Archer's Kanshou and Bakuya. It is an equal fight but with Shirou's new power combined with Toucon Boost they were able to be powerful enough to make Archer struggle.

"Hikaru, let's finish this!" Shirou said.

"Hai!"

Hikaru opened his sword's lens and placed his Ore and Toucon Boost Eyecons into the Blender Furnace.

TOUCON DAI KAIGAN!

Sunglasseslasher is enshrouded by vermillion flames that then heat up the blade to allow a white-hot slash hitting Archer and sending him to his knee.

MEGA OMEGA SHINE!

"Tou-san, finish it!"

Shirou began pressing the RevolTriger many times, activating and summoning all the Damashiis.

MUSHAHI, EDISON, ROBIN HOOD, NEWTON, BILLY THE KID, BEETHOVEN, BENKEI, GOEMON, RYOMA, HIMIKO, TUTANKHAMUN, NOBUNAGA, HOUDINI, GRIMM, SANZO!

RASSHAI! ZEN DAI KAIGAN!

The 15 Damashiis formed by a diamond-shaped Ghost symbol.

KENGO, DENDO, ARROW, RINGO, COWBOY, KYOSHO, MUSO, KAITO, DAZEYO, JO-O, DAI-O, BUSHO, DASSO, DOKUSHO, SORYO, ZEN-IN SHUGO!

GRATEFUL! OMEGA DRIVE!

Shirou jumps up as the Damashiis combining into a powerful fireball for Ghost to use to defeat the enemy with a flying kick hitting the fireball straight into Archer's chest sending him back into a fiery explosion. As the fire died all was left was an unconscious Emiya.

AN: This is what I got. I feel like I could do a story better and I feel like I could make this into a story one day. Either way, this idea was stuck in my head and I wanted to put out here or I get anything done. I also imagine this one-shot longer but you should get the plot idea of this one-shot and look out for this as a possible story.