WARNING: Mildly Warm (High School DxD/FateNasu Chapter 1)

Life is, uh, chaos.

It is completely unpredictable how the smallest changes can result in exponential divergent results.

Issei Hyoudou had just arrived to the designated spot he was supposed to meet his date. A girl in a devil costume arrives and hands him a flyer, about devils, summoning and wishes, which he pockets for now. Finally, Yumma Amano arrives to begin their date, which is all a hoax, as she's actually the Fallen Angel Raynare, in disguise planning to toy with and kill him later on in the most tragic way she could manage.

And here is where the single change occurs.

"So, Issei-kun, are you ready to go?" Said Yuuma as she grabs Issei's arm, leaning into him.

"Y-Yeah, I have it all planned out! You're gonna love it!" Issei said, more to himself really, as he hoped his plans for the date would be enjoyable to her.

Raynare giggled, hiding her disgust and urge to roll her eyes, but anticipating how fun it will be later once she gives this clueless boy a slow death.

Yuuma's phone rings, and the couple stop.

"Eh?" Yuuma took out her phone, looking at the caller, and almost sneered, ruining her act, settling on frowning cutely. "Sorry, Issei, please give me a moment."

"Oh sure no problem." Issei smile, waving her off as he stood to the side.

"Hello~ Mitt-tan, you know I told you not to call me today." Yuuma spoke in her usual sweet voice, listening, making sounds and nodding at what she was being told.

Issei mentally gushed about how cute she was, with her expressions. He blinked as her face her murderous for a second.

"WHAT!?" Yuuma shouted.

But by time Issei blinked and looked back, Yuuma soft face was back, looking concerned. He rubbed his eyes, it much have been his imagination from playing all those BDSM visual novels, with hot evil chicks. Good thing he watched some vanilla playthroughs before his date.

"Um, Yuuma-chan?" Issei said in concern.

"The flight schedule changed? Are you serious? She's there now!?" Yuuma blinked in shock, as she spoke a bit more, before saying her goodbyes and turned to Issei with a regretful look. "Um, Issei-kun, um, sorry but, um see, something came up."

"You need to go right?" Issei said with an understanding smile.

Inside however he was definitely crying. Just his luck, the first time a girl is interested in him, the universe intervenes to make it not happen. Maybe his friends, Matsuda and Motohama were right. That him getting a girlfriend was against the order of the universe or something.

"I'm sorry!" Yuuma went and hugged him. Issei looked up trying to hide his perverted face, as he could feel her glorious chest against his own. She looked at him with a pouty look, tears in the corner of her eyes. "My cousin's flight changed to today, she's actually at the airport right now. I have to go with my friends to get her."

"I-it's okay, I get it-t. These things h-happen really." While Issei was trying to remain calm, and not get a boner, he lightly patted Yuuma on the back, as being touched this much by a girl is an overwhelming experience, and it's already taking his everything to keep his cool.

Yuuma let go to the relief and sadness of the Oppai-loving Pervert.

"We'll go next week, okay!? Same plan, same time, same everything." Yuuma said with a cute pouty look of determination. "I promise nothing will interrupt us next time. Okay? Promise me?"

"I promise, Yuuma-chan! I'll definitely be here next week, and things will be good-no better then even today!" Issei said enthusiastically, as Yuuma bid him goodbye and ran off.

Issei waited till her left his eyesight before sitting down at a bench nearby and crying pathetically.

Maybe this was a sign and he should give up on ever getting a girlfriend, let alone a harem.

The fires of his dream roar again in his chest.

No! He still had next week. The date is definitely still on. It's just an unexpected set back.

He will definitely hold hands with Yuuma-chan next week!

Issei threw his jacket on a chair nearby, and laid down on his bed.

Of course returning so early had his parents make fun of him, saying that obviously his ruse about a girl asking him out turned out false, and he got bored to goofing off alone and came back home.

Issei argued with his parents that the date was postponed, with his father and mother switching between berating him to making up a girl who asked him out, to telling him he should have offered to help her, as it was the gentlemanly thing to do. Also to impress said possible girl so they can finally have a grandchild.

It was that last thought that stuck in Issei's head. It's still early enough, maybe if Yuuma finished up her errands early they can continue their date?

He put his hand in his pocket and took out the flyer he got earlier. It might be nothing, or it might be worth a shot.

"'Focus hard on your desire and we will arrive to grant it'." Issei read the tagline under the pamphlet's title. It had a complicated magic circle drawing on it, and under it instructions on how to activate it, to summon a devil that would help you for a small price, and that prices are negotiable. "Meh, why not?"

Issei didn't see a reason not to try, so he focused on the talisman and his wish and how much he wanted it.

"Oh?" Rias Gremory, a Devil and daughter of the Noble Devil House of Gremory, as well as a school idol in Kuoh Academy, looked at the summoning circle lighting up to tell her of someone with a strong desire trying to summon her. "Issei Hyoudou, huh?" She chuckled. "I suppose him summoning me was going to happen eventually." After all, she had been living in Kuoh Town for years now.

She frowned in disappointment though. "Shame, if he had just called in a different time." Rias was getting a summoning right then, at the same time from an repeat client, and it wouldn't do to ignore your old customers.

Sadly, all her Peerage pieces, those who were her friends and technically servants, were busy with their own contracts.

"Oh well, I'm sure he wouldn't mind waiting for an hour or two."

After all, the prospect of meeting a real Devil, especially a beautiful one such as her, should fix any grievances.

Rias Gremory would come to regret this decision.

"It's glowing! It's glowing!" Issei shouted with excitement as the magic design on the pamphlet glowed. It was real. Magic is real! Issei could feel a sort of aura starting up in a sense...

And then nothing happened.

"Huh?" Issei blinked in confusion as the talisman stopped glowing, and nothing happened.

He tried again, wishing more, wishing harder.

The magic design glowed again...then nothing.

"Is it a dud?" Issei frown, before signing for getting his hopes up.

Looks like no date for him today. He has to wait a week.

"Dammit!" Issei slammed the contract talisman on his desk as he booted up his computer and opened up his copy of the F*te Principal Command game. He wanted to play something with some action and hot girls.

Then an idea came to mind as Issei looked at the iconic magic summoning circle design of the game. The magic circle where the game's protagonist summons hot waifus from across time and space.

And some husbandos, but those go into the incinerator to become Magic Coins. As for Traps? ...He'll get to them. Eventually. He's usually busy playing the game anyways and forgets about them.

The point is, Issei had an idea.

A very, very bad idea.

He took the devil contract talisman, got a presentation paper, from when he had to do group projects for class, some pens, coloring pencils, a ruler, compass and got to work.

It took some dedicated focused work, and some redrawings to get the design right and clean, but it was done.

Issei looked his personal magic circle with pride, having fully mixed the design of the Exemplar Ideal Summoning from the F*te franchine and the one from the pamphlet.

I focused again trying to remember that feeling from when the pamphlet lit up.

Nothing happen.

Because of course a mishmash of magic circle designs, one of which was fictional, wouldn't actually result in a magic effect.

"God dammit it, come on!" Issei shouted in frustration, wishing and picturing a hot, sexy devil that would make his wishes come true. I wished with all his heart. "Come on, come on, come on!"

Then...chaos happened.

Life in unpredictable. There are so many factors that impact our life, that we are unaware of, and could never have thought of or accounted for.

For example, Issei was a human with below average magic potential. Yet the devil summoning circle accounted for that, by using a minuscule amount of the devil being called up's power to jump start the process, and then the spell would use energy from the environment to complete the process.

Issei didn't have the magic energy to continue the process once it started, as the paltry amount of energy in a human urban area wasn't usually a lot. Yet Issei, unknown to himself, was a human housing a Sacred Gear. A miracle from the God of the Bible granted to humanity so they may empower themselves. Not just any Sacred Gear either, but the Boosted Gear, one of the 12 Longini that can slay gods, sealing the Welsh Red Dragon within it.

Issei had no idea who he was summoning beyond a devil. A devil that can grand his wish. His wish to help Yuuma-chan so they may go on their date.

And suddenly it happened. The mind is a mysterious thing, sometimes making connections randomly, and often times, those connections may seem like destiny.

Issei's mind went to Yuuma's face when she was angry. Even angry she looked beautiful.

No, she went from cute to sexy.

Then his mind went back to devil, and then to the F*te game he was playing.

Hot Devil meant evil hot women.

Hot evil women meant bondage.

Bondage meant leather outfit.

Hot sexy ane-sama in leather.

Giant boobs in leather and an ane-sama with an arrogant smirk.

"OOOOOH! YEAAAH!" Issei's imagination went into overdrive. "ANSWER MY WISH, SEXY DEVIL ANE-SAMA!"

Boosted Gear flashed in green light, appeared on Issei's arm in it's true form, filling and almost burning him up with power.

[BOOST!]

The hotchpotch magic circle lit up in red light with wisps of fire glowing out of the drawing.

A few hours later, Rias sighed in her office chair as she had been done for the day. One summoning came, right after the other since it was the weekend, where their job is usually at it's peak, with their clients knowing their working hours being limited, due to Rias and her Peerage being high school students.

She suddenly felt like she had forgotten something.

"Rias, aren't you gonna get that?" Akeno, Rias's Queen and best friend said, pointing to the note Rias wrote to herself about Issei's summon attempt.

"Oh, right, I should get on with that-"

A sudden surprise quake, followed by a loud explosion rocked Kuoh Town as from their window, the Occult Research Club saw a column a fire rise up to the sky from the residential area.

Something so visible would be wide spread and seen by all the mundane humans of Kuoh, thus Rias and her Peerage quickly fly to deal with the situation.

Issei's room was on fire, and he he could only think he was seriously glad his parents weren't around, as they went out on their own date, as if to rub it in that he didn't have his own.

He wasn't glad for their safety. Well, okay, maybe that, but he was still bitter about them announcing how they are going on a date and he was not. Was that their version of encouragement of heading to Yuuma and helping her?

Either way, he was glad they weren't around because, well, he suppose the house being on fire is bad.

But mainly it was the damn sexy tall redheaded woman in front of him.

At some point, Issei had fallen, sitting on the ground, with his bed behind him. The woman had one leg on the bed, a red katana that's on fire, stabbed into the ground, that she used to lean on. she was wearing a full leather onesuit, with a red cape.

And she was smirking at him. Oh god was that smirk giving him some complicated feelings.

"Hahahahaha, quite the adventurous one aren't you?" Her voice had a deep sound, that seemed to demand those that hear it listen, and dare he think it, submit. Something in him roared to challenge that, but he wanted to live for now, so he didn't oppose her. Also, fuck, that body in tight leather. Those boobs held up so tightly! "To think there is a mere mage that would foolishly call upon me, the Pāpīyas of the Demon King of the Sixth Heaven, Oda Nobunaga."

The flames seemed to shoot up in intensity before weighing down.

Wait. What did she say?

"Yet to so bravely, yet foolishly strive forward without care in the fear of annihilation. Very well, I will accept you as my first retainer." Demon King Nobunaga smirked, which sent a pleasurable shiver down Issei's spine. "So go ahead young one, tell me your name, and express your joy."

He could still see her crotch, her breasts and her amused eyes from where he was sitting on the floor.

She said she was Oda Nobunaga.

Oda. Nobunaga. One of the most important and historical Japanese figures was summoned by him, in his room.

Her being a woman wasn't the issue. Anime, Light Novels and games had conditioned him to expect famous historical figures to be hot woman in disguise, even if they don't disguise themselves. All the historians just tripped and wrote them wrong, or something.

The point was, Oda Nobunaga was a very important figure, and regardless of her hotness-blasphemous thought aside-she was asking him to introduce himself.

Him, Issei Hyoudou, Oppai Pervert and wanna-be Harem King. He hadn't even taken that first step to accomplish said dream, yet he was in front of a mythical authority meant to be her First Retainer.

He needed to get this right. He can't fuck this up. He mustn't fuck this up.

You only get one chance to make a first impression, right?

Issei Hyoudou looked up to the patient Demon King, gulped at seeing and remembering how sexy and hot she was-or maybe that's the fire around them. He should panic and do something about that-steeled his nerves and opened his mouth.

"Step on me, mommy."

"...What?"

"What?"

Miles away from Kuoh Town, in the depth of Kyoto under the wards housing the secret Youkai population, in the headquarter of the West Youkai Faction, a certain alarm was ringing out at full power.

It was no secret to being of the supernatural realm that certain humans that achieved great deeds in life would sometimes return in spirit to one of the many humans related to them in some form, allowing them a fresh start, while having the same motivation, drive and skill they had in life. In some cases even returned in a full reincarnation in one of their own descendants.

However there were certain individuals that certain factions would try to ensure they never return, or take them out before they ever leave the crib. Like the Romans and Attila the Hun. Or the British Isles and Balor. Or the Greeks and Paris. But that's mostly because Paris just caused problems by existing, regardless if he mean it or not. He was a walking trouble-maker, just tripping and unintentionally making catastrophes.

And for either of the Youkai Faction in Japan it was Oda Nobuaga.

Usually, just the mere hint of his return and the youkais would immediately spring to action, along with even some help from the Shinto Gods in the background. The event would be something only the Leaders of the Youkai Faction would know about, and take care of in secret.

The strength of the alarm now is because not only had Nobunaga returned, but had done so fully matured and with his full power.

They needed to act now before Japan is engulfed in war again, let alone the masquerade being broken.

"Where is the signal coming from?" Yasaka demanded of her advisors.

"Kuoh, your ladyship." Said one of her tengu generals. "From the devils' territory of Kuoh."

AN: The title is a lie.