Here's option two for the crossover story. In this one, rather than having the world of MHA shift to accomodate for the worldwide phenomenon that was Duel Monsters, Izuku alone will be the one to utilize this ancient power. Duel Monsters as a game will still exist as would the events of the original Yu Gi Oh! Series and Gx, but it will be much more contained than it was.
The game still exists, Duelist Kingdom, Battle City, and Duel Academy still happened. But the consequences of these events were limited to the general area. Japan at most. Duel Monsters still became an international game, but simply never becomes a global phenomenon like it did in the original. It merely continues to exist as a fairly popular game rather than a lifestyle.
This is the story of how one Izuku Midoriya uses nerd powers to discover the conspiracies surrounding the game and discover the ancient magic for himself. Ah, and I'll be explaining the timeline at the ending A/N.
"Duelist Kingdom, Battle City, that one time Kaiba Corp holograms apparently malfunctioned, and a seemingly random trip to Egypt? I refuse to believe that all of the strange things that went on in these events were coincidence." Izuku muttered in the dead of night as he did research. All of which revolved around three key people. Each one was special in their own way.
First and foremost there was Mutou Yugi, a seemingly normal teenager with a talent for games who, practically overnight, became somewhat famous by defeating the then Duel Monsters national champion Seto Kaiba followed by his victory in the Duelist Kindom tournament. A tournament that earned him the title of King of Games.
A tournament that had dozens of mysterious disappearances linked to it. A tournament that was held by Maxamillian Pegasus, the creator of Duel Monsters and the second key person in Izuku's puzzle. Specifically because of the suspicious circumstances behind the creation of his game. A random archeologist discovers an ancient Egyptian tomb and randomly creates a card game that quickly became one of the most popular games in Japan?
Never mind the fact that he came back from Egypt with a mysterious golden eyeball that he somehow lost during the events of Duelist Kingdom. Or that Mutou Yugi held a similar artifact which was confirmed to be a genuine ancient puzzle discovered by his grandfather Solomon. Or that the third person of interest on Izuku's list, Marik Ishtar, and his siblings had two more of these artifacts.
Millennium items, he learned that they were called. Ancient Egyptian artifacts dating back to the first millennium B.C. Any further description was vague at best, but it was said that these artifacts each had magical powers attached to them. A claim that once would have been ridiculous to many...Before the emergence of quirks that is.
Nowadays, the impossible was just an everyday occurrence.
So, Izuku did a bit more digging. Why you may ask? Simple, he was out sick with the flu for a week and he was bored. Plus he already had a hobby of studying superpowers anyway so ancient shadow magic was the mental equivalent of a stone throw away. Some of the greatest legends began with the most mundane of things after all. Whether that was the completion of a puzzle, being late to an entrance exam, or even a simple illness and curiosity.
From his research into millennium items, he heard stories about the creation process and tragedies involved with a certain set of cards. The Egyptian God cards were yet another instigator of strange events whenever they were summoned. Including several injuries, incidents of comas, and even deaths...Which came from a few pieces of cardboard, Izuku stressed.
"There has to be something deeper here. Even if you try to rationalize all of this nonsense, that still does nothing to explain away...Whatever the hell happened to Duel Academy." Izuku muttered mid-research, it happened a while ago but it hit international news when it happened.
A whole school campus with a comparable size to a small city simply disappeared one day. Completely and utterly, even the piping disappeared leaving nothing behind but a barren crater at the center of an island only for it to reappear a few short days later. Nowadays, people explained it away as an early manifestation of quirks but knowing what he did now, Izuku called BS.
Well, he knew what he was buying to pass the time this weekend. It was time for him to learn how to play Duel Monsters.
Years and many many close calls later
"Deku, what the fuck are you thinking, signing up for U.A?! Just because you got your shitty quirk late doesn't mean you stand a chance. I'm supposed to be the only one from this shitty school who made it in!" Katsuki's inferiority complex was showing again, it had been months since he spoke to Izuku and he finally broke the silence when his misplaced pride was in danger.
About that quirk he mentioned, well, it was a pain in the ass for Izuku to rationalize and get past quirk registration that's for sure. But in the end, Izuku did what he did best. He got creative.
Midoriya Izuku, quirk: Life Force Summoning(Emitter): Izuku Midoriya passively generates an energy source that he can use for various things, most commonly for summoning powerful monsters with special abilities. However, these monsters always have specific limitations. They mimic the cards of the popular game Duel Monsters due to Izuku's familiarity with them.
All of this was a thinly veiled excuse for his magic of course. At first, Izuku could only do very basic things with his life energy; strengthening his body, minor healing abilities, illusion crafting, and a bit of spell casting using his cards as a medium. However, over the years things changed, he wasn't just using his own powers anymore.
"Don't sell yourself short partner. We may act as the catalyst for your powers, but the energy still comes from you." A vaguely western voice spoke in his head, though in the context of telepathy, 'voice' was the wrong word to use. More like it had the...Feeling of being western, if that made any sense.
'So in other words I'm an irreplaceable battery.' That made Izuku feel so much better...No offense to the Batterymen. 'We seriously need to work on those confidence issues of yours.' Elemental HERO Captain Gold said before 'leaving' Izuku's mind. The frontrunner of his current deck having said all he wanted to for now.
"Don't you fucking ignore me!" Another yell and Izuku assumed an attempt to startle him with an explosion. He assumed because Izuku pre-emptively spritzed the blonde with a quick usage of Bubbleman's water element. It was such a tiny usage of magic that Izuku could have done it a thousand times over before getting tired, but it was still enough to dilute the blonde's sweat and dampen any explosions he tried to make.
Or at least the kind of explosions that the bomber was willing to whip out in the middle of class.
"They're at it again. Who would have thought that Izuku would get a quirk that versatile? At this point, I can't tell which one is stronger." A student that was in the same class with him during his earlier years. Those that once ridiculed him for being quirkless now looked at him in a similar way to Katsuki. Though with respect instead of fear because of Izuku's much more neutral personality.
Most would say kind personality but not here. Izuku was having none of their bullshit. Did they really expect him to just accept their heel turn after years of bullying? The passive boy would never say it out loud, but fuck 'em. Those that didn't know him from back then got a fair shake though, it just so happened that most were just as quirk obsessed and unworthy of his friendship as his old bullies.
'Such a rotten bunch, what's with this school that attracts so many brats?' He knew that such views were at least somewhat common in society, but at least most people kept the quirkism somewhat hidden away from polite company. These kids didn't even try to hide it.
'Whatever, none of them are worth the headspace. Now about that new Hero fusion that's been making waves…' This was how most of his days at school went these days. Much like Katsuki, Izuku easily kept up with his studies and barely needed to pay attention while in class.
That was one benefit of having a good quirk Izuku would admit. The teachers let them both do whatever they wanted so long as they kept their grades up to a reasonable level. Considering they were the top 2 students in Aldera, nobody bothered to stop them from goofing off during the day.
Not that they did, they spent every second of their time constructively. Katsuki did so by studying pro heroes and coming up with new ways to use his quirk. And Izuku. Well, he was on his phone, for the most part, constantly going over simulations for his cards, dueling other players online, and writing notes for anything that he picked up along the way.
نيو سبيس: يستحق نظرة. الخلد قوي ، قد يكون نيو نفسه مفيدًا
Izuku wrote his notes in Arabic, a language that he needed to learn at least the basics of for his earlier research. Nowadays he didn't use it for much else but it was a good way to remember his roots. And a great way to keep nosy teenagers from snooping where they had no business. And it pissed off Katsuki who was always mediocre with foreign languages, which was a bonus.
Later that day, Dagobah Municipal Beach
"Hmm, this archetype really isn't my thing. Maybe if it had a bit more protection to it but that bootleg Gladiator Beast drawback is just not worth it." He never did get over his muttering habit though. At least he did manage to keep his muttering to a minimum and made sure to filter any incriminating information that came out of his mouth.
Now you may be asking, why was he in Musutafu's very own public beach turned dumping site? Training of course, or more accurately, experimenting. "First Sparkman's electromagnetism to power and move all this metal, next, a bit of Avian's aerokinesis to get things moving and to provide a fluid for the electricity." Piles of iron, steel, and other ferrous metals rose over Izuku's head, sparks visible to the naked eye and dancing across each piece.
"Next, plenty of heat from Burstinitrix to melt it all down." The energy expenditure was high but the inferno created by his soul's energy eventually turned the various pieces of garbage over Izuku's head into the molten metal which he could manipulate even more freely than before.
"Now to put this stuff to use…" The metal slowly cooled down, a bit of water manipulation from Bubbleman helped with this process and was placed down in neat symmetrical sheets to be used later. Izuku made absolutely sure that they were each heavy enough and shaped in such a way that no errant tides would take them and undo all his hard work.
"Tomorrow, wow that was exhausting." If he had kept going in his current state he might have passed out before the job was done...That wouldn't have ended well. It would seem that utilizing the powers of multiple monsters simultaneously and in such quick succession was going to have to wait.
"That was rather impressive young man, would you happen to be training for the hero course?" Despite his exhaustion, Izuku nearly jumped straight up into the air in surprise. Turning around, he saw a...frankly unhealthy looking blonde man whose blue eyes were so sunken he mistook them for having black irises for a moment.
The greenette coughed into his hand to steady himself. "You saw that huh, sorry about the public quirk use but I thought I'd be alone here and there's finding a place to practice is rare." Honestly, how did they expect people to become worthwhile heroes if they couldn't even practice their abilities? At least for people that weren't rich enough to afford a fancy quirk gym membership.
Damn things cost a mint and weren't worth the trouble as far as Izuku was concerned.
The blonde man shrugged. "You're the reason anyone is coming here in the first place. Or was it that some teenager that kept cleaning this place up for the last few months? Don't worry about it kid, a friend of mine works for the police and they got your back. They just can't be too public about it." If they could they'd be offering the teenager a medal, not a reprimand.
"U-uh, thanks I guess? I was just practicing anyways. Cleaning this place up didn't really factor in until later, it was more of a bonus." He did it for his own benefit, but it did feel good to see that his efforts did something positive.
Another shrug from the blonde skeleton. "A good deed done for selfish reasons is no less commendable than one done out of pure altruism. The hero industry would be far smaller if people truly thought that it didn't. Anyways, I just came to congratulate you and maybe finally get the name of the young man who made this place beautiful again." ...There was something about this man's smile and face that was familiar. In more ways than one.
"Izuku. My name is Midoriya Izuku, and I'll be attending U.A if you were wondering." The man's smile widens, showing his teeth. The weird feeling of familiarity intensifies.
"An excellent choice. Well, it's about time for me to go, good luck my boy, I'm sure you'll do just fine." Izuku almost called out to the man before he left but decided not to. What he had was probably just a misplaced feeling anyway. He needed to get home soon anyway.
Day of the entrance exam, Training Ground Beta
'Other students are preparing their quirks ahead of time. Ok then, that means this should be fair game.' Izuku closed his eyes and concentrated on his soul power, summoning Avian first since he had the most mobility, shocking his fellow contestants with his sudden appearance. Izuku paid them no attention though, he was too focused on actively regenerating his soul power as quickly as possible.
'Next, some firepower.' Izuku waited until his soul power was back to full before summoning Burstinatrix, and once again the other wannabe student's attention was caught by her arrival. Though for slightly different reasons.
"Damn she's hot...In more ways than one, I think my balls are melting." The weirdness of that sentence snapped Izuku out of his concentration just in time to hear Present Mic's call to start. That was all he needed to hear.
"Avian, find the area with the most robots and signal me, Burstinatrix you're with me, let's go! LEEROY-" Izuku ordered, manipulating fire and wind on his own to propel himself and keep pace with Burstinatrix as the two rushed towards the fake city and the robots they could see.
"Oh my god, he just ran in."
With Izuku and Burstinatrix
"Thank you for letting me out summoner, a battle against robots in a huge city...I'm feeling nostalgic." Burstinatrix said happily, launching streams and balls of fire that melted and/or blew up the mass-produced automatons with ease.
"I should be thanking you for helping me out, but I'll guess we'll call it even." A feather fell from the sky and landed sharply in front of Izuku. "That's Avian's signal, keep up the good work Burstinatrix, I'll head over there." He gave his instructions before running, unaided by magic this time since he wanted to store some up for another summon.
It was also around this time that the majority of the other wannabe students joined them. Or Burstinatrix anyway, Izuku didn't give them a glance, too focused on following Avian's flight path. "Aw come on, he hardly left any for the rest of us. Whatever, wherever that kid's going, I'm heading in the opposite direction!" Random teenager number 29 said before doing just that, he was followed by a large group of others but a select few thought otherwise.
'That guy knows something we don't, even if it's just the scraps I'll be better off following him!' Two people, one a brown-haired young woman and the other a stiff but steady blue-haired young man had very similar ideas and took off towards where Izuku went running. Though one was considerably faster than the other, having engines in his legs and all.
"He went this way, and if this city is at all similar to Musutafu then there should be an open area somewhere around...Oh my." The area was almost completely flooded, along with having dozens of robots thrown around, most of which were seemingly deactivated but a few simply couldn't move properly with all the water around.
It felt a little underhanded to capitalize on another student's achievements, but the green-hairedboy didn't leave him much choice. Besides, even All Might relied on other heroes to hold down and arrest villains while he dealt with greater threats. That being said… "My engines aren't exactly good with water either." Oh well, he'd just have to take out the ones in the shallow areas.
"I think I saw those two coming this way, I got ten points on my way here so that's gotta be a good sign right?" At least Ochako thought it was pretty good, they didn't exactly know how many points were needed to pass, or even if there was a hard cut-off. "I can't worry about that, for now, I just have to focus on- whoa!" Did a flood hit this place or something? Wait a second, there's that green-haired boy from earlier, just sitting on top of a 3-pointer.
"Hm? Don't mind me, I'm just resting after letting out a big attack. Feel free to take some points for yourself." Ochako was about to ask whether he was sure but decided against it. Time was running out and she was taught not to be picky.
"Thanks! I owe you one!" And so she went, joining the Tenya in the robot killing, but keeping her distance to minimize conflict. The robots deeper in were easier for her to get anyway thanks to her gravity powers, they made moving them out of the water and crashing them into concrete very easy. Though her stomach was doing flips by the end of it.
"Do your gravity powers mess with your equilibrium? Too bad, it's still a really impressive quirk." Ochako jumped in surprise and turned to Izuku who...Was taking notes? Were those notes about her? "Not just you, I take notes on any quirk that I find interesting, I have that engine guy's quirk in here too. And yes, you were muttering, don't worry about it I do it all the time too."
Seeing that she was in a similar situation and probably wouldn't be able to keep going without a short rest, Ochako decided to join the boy on his robot and took a look at his notes for herself. 'Holy crap how long has he been watching me?! Or did he figure all of this out with just a glance?'
She didn't know which one she was more afraid of.
*Rumble
"Hm, so that's what Present Mic meant when he compared it to a thwomp." The boy said oddly calmly when there was a gigantic fucking robot looming over them...Was it just her or were its 'eyes' staring at them directly and glowing menacingly.
"It probably is, I think it's programmed to chase after the closest student to it since it didn't even look at that blue-haired guy when after he ran off. Lucky us." ...Was this guy ok? How and why was he so calm, he almost sounded...Bored?
"That's because I am, that thing is big sure. But it's painfully slow as long as nobody gets injured or stuck they could easily outrun that thing. It can barely even fit through those buildings." So they were just going to...Walk away? Lightly jog away? "That would be the easiest option unless you want to look around and check to see if others need help. Though I already have those three on the job."
"Wait what? Who are you-Woah!" How did she not notice them before? A trio of pro heroes was running across the whole city, flying people to safety, melting the streets to slow down the zero pointer, and even offering water to people that needed some. "Who are those people? And why do they look so familiar?"
"Well, to answer both of your questions, they're part of my quirk and you've probably recognized them from these." Izuku held up three cards, one for each of the heroes that Ochako saw around her. Those were...Duel Monster cards right? She had heard about them before but never got into the game since it was pretty expensive.
"That depends on whether you know where and when to buy certain cards. Buying packs can get pricey that's true, but singles are a lot easier to manage and without the need to rely on luck." TIMES UP! "Looks like it's all over, sorry for holding you up like that, oh well, I'm sure you earned enough points to pass anyway."
"Y-you think so? I certainly hope so, ah! My name is Uraraka Ochako by the way, we've been talking this whole time and I never asked your name." It was then that she saw the boy smile for the first time since they've met...Huh, he should do that more often, he looked a lot better like that. And now he was blushing...She said that out loud again didn't she?
"Yup. And thanks I guess, my name is Midoriya Izuku. Nice to meet you." Little did they know that their first meeting was going to be the start of something far deeper. A heroic partnership that would make waves across Japan and eventually the whole world. But for now, they had to deal with their first and most insidious enemy.
Teenage awkwardness
That's all for this one. To summarize this Izuku's powers, think shadow duels from season 5 of Yugioh mixed with what Judai could do during season 4 and onwards of Gx. Izuku can expend his life force to summon and use the powers of cards with his own body.
Summoning takes more energy and he can only summon one or two monsters at a time before needing to recharge. Monsters also take a set amount of energy to maintain their forms, so even with recharging reserves, he's limited to summoning a certain number of monsters at any given time.
Using a card's effect on his own is easier and takes less energy, but the effects are significantly weaker than if he used a monster's body as a catalyst...I think that's about it.
Now for the timeline. The events of Yugioh and Gx happened in the 1990s and mid 2000s respectively, meaning that humanity in this world had a small bump to technology, specifically with holograms during this time. The first appearance of quirks happened sometime during the 2030s while the main casts of Yugioh and Gx were in their 50s and 40s respectively. From there, four generations of quirks pass, until we get to Inko, making Izuku part of the 5th generation after quirks appeared. Or roughly a century later.
That means that the year that this story takes place is roughly in the 2130s. And in that time Duel Monsters has survived as a game but eventually lost the rabid fanbase that it used to have during the time of Seto Kaiba. Do with that what you will.