Izuku Midoriya and Katsuki Bakugo had just lunged at one another. Both boys were charging massive attacks with their Quirks, Midoriya with an uppercut and Bakugo with an open-handed right hook. Time seemed to slow as the boys raced towards an explosive collision.

"Detroit..." Midoriya shouted as Bakugo snarled. All Might was about to use the communicators in their ears to tell the boys to stop. Before he could do so, there was a flash of light and Riku appeared between the boys.

In that moment, time seemed to slow for Riku, Midoriya, and Bakugo. Riku realized the danger and created a Dark Barrier around himself to protect him from the two boys that were hurtling towards him. Midoriya and Bakugo simultaneously realized that neither of them could stop their momentum or their Quirks in time to avoid the sudden newcomer. Midoriya panicked and shot his uppercut off early, causing him to turn 180 degrees in the air. "Now, Uraraka-san!" he shouted as his momentum continued carrying him towards Riku.

At the same time, Bakugo snarled. "Outta my way!"

Midoriya and Bakugo collided with Riku's shield of energy at the same time as rubble began falling from the ceiling, where Midoriya's uppercut had sent a massive wave of pressure. The force of the impacts from both boys and the rubble sent cracks lacing across Riku's shield, and forced the walls of the shield in. Midoriya was knocked unconscious by the pain in the arm he had punched with and from the impact. The shield shattered and Riku's Keyblade vanished, but both boys' momentums had been slowed enough for Riku to catch Midoriya and for Bakugo to land on his feet and slide to a stop.

Riku was knocked back by the remaining force of Midoriya's impact, and Midoriya had fallen unconscious. Bakugo looked shocked and furious. He marched towards Riku and Midoriya as All Might ran up with two robots that were holding a stretcher.

All Might stopped Bakugo with a massive but gentle hand on his shoulder. "Let's head back, Young Bakugo. Time for your grading." The two robots loaded Midoriya onto the stretcher and carried him off. "Whether you win or lose, you can always come out ahead by learning from the experience."

Bakugo stormed off. All Might looked to Riku, his eyes glinting with suspicion towards the silver-haired teen. "Young man, what just happened?"

Riku thought for a second. Something isn't right. I'm about the same height as those kids, but they've got to be three or four years younger than me. Did my body change to fit the world? Must have… and I feel strange after that impact. Best to just play along. "I'm not really sure. I was looking for a friend, but I somehow found myself in the middle of that fight. Sorry if I interrupted something."

"W-Well…" All Might looked in the direction Bakugo stormed off, seeming thrown off by Riku's calm demeanor. "You certainly were a surprise obstacle for those young students."

Students? thought Riku, and he looked around at his surroundings. This doesn't look like a school… Riku suddenly flinched as pain shot up his left arm. "Ouch!" He grabbed the injured arm with his good hand. He must have jammed it when he caught Midoriya.

All Might's composure returned. "Why don't we get you to the infirmary for now, young man?"

Riku looked at his injured arm, which seemed to be badly bruised. "Yeah, that sounds like a good idea."

All Might turned around, then looked back to Riku. "Young man, I am All Might."

Riku stood, still clutching his injured arm. "I'm Riku." The look All Might was giving Riku gave him the impression that they would be talking about the situation soon. Riku gave a small nod and All Might led him towards the infirmary.

...

Riku sat in the infirmary bed, thinking over everything he had seen on the walk to the infirmary. He was most certainly in a school, albeit an odd one. The place he had appeared in was a mock city, it seemed, and the "students" Riku had interrupted were in the middle of what appeared to be a very intense mock battle.

All Might had run off just after he and Riku arrived at the infirmary, saying that he had to evaluate the students and continue their class. Riku looked at his now-bandaged left arm, which the nurse, Recovery Girl, said had been jammed by the impact of catching Midoriya. Riku adjusted himself uncomfortably, thinking back on how Recovery Girl had kissed his arm. It was definitely weird how her face moved like that, but it made me feel like a little kid again…

Recovery Girl walked up to Riku with a bag of ice. "Here, this should help with the pain while your arm heals."

"Thanks…" Riku placed the ice bag on his arm.

"Now, All Might told me to answer any questions you might have, and I'm guessing by how quiet you've been that you have quite a few."

Riku looked to the curtain next to him, behind which Midoriya was sleeping. "Well… First, is he okay?"

Recovery Girl sighed. "He would be better, but he has an idiot for a mentor. I can't say too much about it unless All Might wants to share, unfortunately."

Riku looked back at Recovery Girl, somewhat confused. He shook his head and continued with his questions. "Where am I?"

Recovery Girl was clearly surprised. "This is UA, the high school where many of Japan's top heroes learned the basics of being heroes."

Riku went quiet once more, looking thoughtful. Heroes… So those kids must have been training to become superheroes. He chuckled to himself.

"What are you smiling about?" asked Recovery Girl, visibly confused.

"Oh, sorry. I was just thinking about how my friend would love this place."

Recovery Girl's expression became more serious. "Well, I think telling you too much more or asking you the questions on my mind would be overstepping. After I tell All Might about his student's condition, we ought to have him and some of the other teachers talk to you." She walked to the chair at her desk.

Riku nodded. "Okay."

Just then, All Might ran in and shouted "I am here!" before transforming into a scrawnier, more bedraggled version of himself in a puff of smoke. Riku jumped in shock and All Might coughed a little. A bead of sweat slid down All Might's face as he slowly turned his head towards Riku. All Might stared at Riku for a moment, and Riku stared back. All Might coughed into his hand and quickly stood up straight. "D-Don't tell anyone about this, Young Riku. Only a few people know."

Riku nodded slowly, still trying to understand what he just saw. Recovery Girl huffed and began berating All Might. "The year's only just started, and this is Izuku Midoriya's third time here! Why didn't you prevent this, All Might?!"

"M-My apologies, Recovery Girl…" All Might looked down with another small cough, embarrassed.

"It's not me you need to apologize to! Yesterday and today, he's come to me completely fatigued! This isn't so easily healed, you know! I've given him emergency first aid and an I.V. drip, but now all we can do is wait for him to recover on his own! Come on… I know you-" Recovery Girl stopped herself and glanced at Riku, further confusing him.

All Might sighed. "He has already seen me in this form. I will likely have to explain everything to him anyways, so there is no need for you to hold back."

Recovery Girl nodded. "I know you gave the boy your power, but whether he's your favorite or not… You have to stop indulging him!"

All Might scratched the back of his head nervously. "You're absolutely right. I was sympathizing with him too much… So, I hesitated. But… Um… I know I said you didn't have to hold back, but can you keep it down? At least when discussing One For All…?"

Just as Recovery Girl was about to retort, Riku finally regained his composure and interjected. "One For All? Gave him your power? What do you mean by all that?"

All Might and Recovery Girl looked at each other for a moment. "Well, Mr. Natural-Born Hero? Mr. Symbol of Peace?" said Recovery Girl in a rather sarcastic tone.

All Might sighed and returned his gaze to Riku. "This true form of mine and the injury that forces me to return to it are common knowledge to the staff here at U.A. However, only Recovery Girl, the principal, an old friend of mine, and Young Midoriya here know about my Quirk. It's a secret to all others. Well, except for you, now, Young Riku."

"If you're so injured, why is it so important to keep it a secret?" Riku's head was filling with questions quicker than he could ask them.

"My thoughts exactly!" said Recovery Girl. She huffed, clearly annoyed with All Might.

"Without me, this superhuman society would fall to evil." All Might's eyes showed intense determination, causing Riku to feel surprise and admiration. "This is the responsibility that those who wield this power must bear!"

Recovery Girl's face softened as she bowed her head. "Then it's all the more important that you learn how to guide Izuku properly, All Might."

All Might looked down as well, seeming somewhat ashamed. He looked to Recovery Girl. "Would you mind letting Young Riku stay here until classes have ended for the day?"

Recovery Girl looked up at All Might, her face returning to a stern expression. "Very well. I'm assuming we'll be having him explain himself to Principal Nezu?"

"That would be best." All Might's gaze returned to Riku. "And we should answer his questions, as well."

...

A while after the final bell of the day sounded, All Might had returned to the infirmary in his muscular form to take Riku to the principal's office. By this time, Riku's arm was completely healed, and he no longer needed ice or bandages. Riku looked up at All Might as they walked.

"So… How do you do that? Change into this form, I mean."

All Might laughed heartily, then coughed and cleared his throat. "You know how people will suck in their guts and puff out their chests when they go to the beach to look more muscular? It's just like that!"

Riku wasn't convinced. There's no way it's that simple…

After a few more moments of walking, All Might turned to face a door that looked just like any of the others in the building. "Young Riku, we are here."

The door opened, allowing Riku and All Might to enter the room. Riku looked around to find the principal he was supposed to be meeting. All Might shrank into his true form as the door closed behind them. "Hello. You must be the young man Recovery Girl told me about," came a voice from below Riku's line of sight.

Riku was mildly surprised by the voice. He looked down to find the source, and his gaze fell upon a small mouse-man with a scar over his right eye. Riku's surprise quickly faded and he nodded. "Yeah. My name is Riku."

"Oh?" The mouse-man's head tilted out of curiosity. "You don't seem as surprised as most by my appearance." All Might glanced at Riku, also seeming rather curious.

"Should I have been?" Riku asked, confused.

The mouse-man chuckled. "Actually, your reaction is rather refreshing. I am Nezu, the principal of this school. All Might, Riku, please come sit." Principal Nezu walked over to a pair of couches that faced each other and climbed onto one. All Might and Riku both sat on the couch facing the one Principal Nezu was sitting on. "Now, why don't we discuss what happened and why you are here, Riku?"

Riku looked down, realizing he would have to break the rules King Mickey had told him about in order to gain the trust of All Might and Principal Nezu. He looked back up before speaking in a cautious tone. "You might not believe me, but I'll tell you everything I know." Riku gathered his thoughts as All Might and Principal Nezu stared at him expectantly. "I'm from another world. I came here to look for my friend, a boy named Sora-"

"You're an alien?!" All Might suddenly interrupted.

Riku looked at All Might with a mixture of disbelief and shock at the hero's sudden outburst. It was such an astonishing conclusion that Riku couldn't believe All Might had just said it aloud.

Principal Nezu chuckled. "I suppose you should explain what you mean by 'another world' before you continue."

Riku nodded, still baffled by All Might's conclusion that he was an alien. "I'm human, just like you." Riku shook his head to clear it, then continued. "The world I'm from is a lot like this one, but we have magic instead of the powers you call 'Quirks.' My world is also splintered into smaller ones, separated by the Ocean Between where portals and spaceships are used for travel. There are a few other larger worlds mine is connected to, but none of them were as difficult to get to as this one. I got here through a portal that was supposed to take me to Unreality, a place where I could save a good friend of mine. He disappeared about a year ago when he used a special power the wrong way to save the world."

The room went completely silent as All Might and Principal Nezu processed what they had just heard. Principal Nezu was the first to speak. "What is this 'special power' your friend used?"

Riku looked thoughtful. "The best way to explain it would be to show you the reason he could use it. I have that same power, and the factor that let me learn it. Just... Please don't panic when it appears."

All Might gave Riku a questioning look. Principal Nezu nodded. "Very well. Please, explain away."

Riku nodded and put his hand out. His Keyblade appeared in his hand. "This is a Keyblade. I'm what's known as a Keyblade Master. Sora, my friend who disappeared, didn't become a Master, but he also has a Keyblade. He and I have the power of waking, that 'special power' I mentioned. It's used to wake up a person's heart when it's fallen into a sleep it can't wake up from. To do that, it lets those with a Keyblade traverse hearts to reach worlds. Sora used the power to traverse worlds to reach the hearts of the people who helped him save the worlds. Including me." Riku looked down as his Keyblade vanished, the memories of Sora's bravery making him long for his friend all the more.

All Might looked down, seeming to realize the weight of what Sora did. He grew into his muscular form, a thunderstruck look in his eyes. "This 'Sora' seems like a true hero! I would love to meet him!" All Might shrank back down to his true form with a small cough.

"He is. And that's why I have to save him." Riku chuckled. "I always have to wake him up..."

Principal Nezu chuckled. "It seems we will have to help you find your friend, then."

Riku looked up and stared at Principal Nezu, shocked. "You would do that?"

All Might smiled. "Wouldn't you?"

Riku looked to All Might, still surprised. After a moment, he smiled. "Yeah, I would."

"Now that you have told your story, I believe it is time for us to answer any questions you might have," said Principal Nezu.

"Indeed," said All Might. "Ask away, Young Riku!"

Riku thought for a moment. "Well... I know I'm at a school for superheroes, and that there are enough people with superpowers in this world to make that necessary. And those powers are called Quirks, right?"

All Might nodded. "You pick up on these things quickly, don't you, Young Riku?"

"I've had to since I was a kid. Anyways, my only question is what do we do now? I don't even know where to start looking for Sora."

"Hm... Yes, that does pose a problem..." said All Might thoughtfully.

"You could become a student here for the time being," said Principal Nezu, an almost mischievous look flashing over his kind smile for a split second. All Might looked bewildered at the suggestion, prompting Principal Nezu to add, "You could be his recommendation, All Might."

Riku looked to All Might for an answer. Small beads of sweat formed on All Might's forehead. "W-well... I suppose it won't be too much of an issue, as I am only a recommendation-"

"Very good! Riku, I think it would be best to place you in Class 1-A." Principal Nezu was visibly happy that his proposal had been accepted. "I will tell Eraser Head, your new teacher Mr. Aizawa, about your situation, Riku."

All Might leaned over to Riku and whispered in his ear. "Be mindful of Eraser Head's physical exams. His grading is tough on the first one..."

Principal Nezu got up off the couch. "I will start making the necessary preparations for your enrollment right away." He went to his desk. "But first, we need to register you. We should also determine how to classify your magic as a Quirk, and name it."

"Name it?" Riku asked.

"Every Quirk has a unique name, such as my One For All," explained All Might. Riku nodded in understanding, and All Might continued, "What is your magic like? What kinds can you use?"

Riku thought for a moment. "Well, I can use a few kinds. The element I use best is darkness." He lit a ball of dark fire in his hand to demonstrate. Riku noticed that the ball of fire was smaller than he wanted it to be, and quickly put it out.

"And that strange barrier you used in the training ground?" All Might was clearly curious about the magic.

"That was Dark Barrier. I can use a few other abilities based off darkness, like one that lets me move faster for a short distance."

All Might was clearly impressed. "How does that ability work?"

"I sort of melt into the shadows, I guess." Riku paused. "I should tell you that my abilities suddenly got weaker after I got hit by those two boys."

All Might looked apologetic. "I apologize, Young Riku. They have very powerful Quirks, and I tried to stop them, but your appearance surprised me..."

Riku shook his head. "It's okay. I kind of appeared out of nowhere." Riku scratched the back of his hair, embarrassed.

Principal Nezu interrupted the conversation. "It's likely best that your powers were weakened, so you will be on a similar level to your classmates. Do you think you can manage using only your darkness-based powers?"

"I think so," replied Riku.

Principal Nezu started jotting down some information on papers he pulled from his desk. "Now, what shall we name your 'Quirk'?"

Riku thought for a moment. "Maybe... Dark Shadow?"

"That's the name of Young Tokoyami's Quirk, and they are too different to justify using the same name," said All Might. "Perhaps Shadow Magic, since you can melt into shadows?"

Riku shook his head. "Doesn't fit with all my abilities." He tried to think of other names, but he could not come up with anything better than his initial attempt.

"Why not call it precisely what it is?" interjected Principal Nezu. "Dark Magic, perhaps?"

Riku and All Might looked to Principal Nezu, then to each other. Riku nodded and looked back to Principal Nezu. "Yeah, that sounds good."

"Very good." Principal Nezu finished writing and aligned the papers on his desk. "I think we are done here, then. Thank you for staying so long, both of you."

"Of course," said All Might. He looked to Riku once again. "Come, Young Riku. I will take you to a place you can stay until we can find more permanent lodging for you." All Might headed towards the door to leave. Riku nodded and followed All Might to the door.

"Come to my office early tomorrow morning so I can give you your uniform and gym clothes. Before you go, remember not to use your abilities in public unless absolutely necessary to comply with the laws regarding quirks."

Riku nodded once more, then left with All Might.