Devil Fruit System in MHA

Kai waited outside Classroom 1A to meet Midoriya and Shinsou for quirk training. He had ten minutes until the bell rang for the end of the day, so he was using his Tinker Fruit to cobble together some scraps he carried around in his backpack. He was currently using a handful of rubber bands, some spare metal parts and a busted pocket flashlight to make a miniature catapult.

He rapidly disassembled the catapult and made a small revolver instead, complete with rotating barrel. He took some thumbtacks from his bag and loaded them into the chambers and pulled the trigger. They went a solid ten feet before petering out and hitting the floor.

"I'll never get over that." Kai decided. "That's just so awesome. Anything I can think of is just made."

Kai reflected on his newest quest;

'Party in the USJ'

 You didn't have to get involved in the USJ situation, but you decided to anyways. Good for you. Hell, you even got yourself some backup.

 Secure assistance for the USJ Situation (3/3)

 Guarantee your own survival (0/1)

 Prepare emergency Empowered Fruits (0/3)

 Rewards for completion- Devil Fruit Spin, Full Heal Voucher, Inventory Upgrade.

He'd already finished the first condition instantly by having Nezu, Ectoplasm and Snipe come with class 1A. The third condition was easy as well, all he needed was to gather healing energy and durability energy. The second condition was the kicker though. 'Guaranteeing' his survival was difficult, if not downright impossible.

The end of day bell rang, snapping Kai out of his thoughts. He stashed his tiny revolver in his pocket as members of Class 1A flooded out the door, most of them looking at him curiously, but electing to ignore his presence. At least, that was until—

"What the fuck are you doing here, extra?" snarled Bakugo Katsuki.

Midoriya came rushing out the door like a fire alarm went off. "Oh hey Kai! Kacchan, Kai is here to help Shinsou and I with after-school training."

Bakugo's scowl deepened as he looked between Kai and Midoriya, irritation— and was that envy? —flashing in his eyes. "Help you with training? Tch. That's just like you, Deku. Always refusing to get stronger on your own, always needing someone to hold your hand."

With that, Bakugo shoulder-checked Midoriya, sending the smaller teen stumbling. He shot Kai a final glare before stomping off down the hallway, leaving a trail of muttered curses in his wake.

Kai raised an eyebrow, glancing at Midoriya. "Is he always this... pleasant? Or is today an off day?"

"Oh, that was one of his better moods," Shinsou said from beside Kai, who hadn't noticed him approach. "At least he didn't try to kill you."

Midoriya let out a nervous laugh. "C-Can we just get going? Please?"

Kai relented with a grin and started walking. "Alright. I've got Ground Gamma booked for after school today, so we can head there for training."

"How did you book an entire training ground?" Shinsou asked, raising an eyebrow. "Much less for an entire day. The most you can do is block out a portion for a couple of hours — I've checked."

Kai chuckled. "Oh, right, you guys don't know. I'm officially a direct student of Principal Nezu now, which comes with certain... perks. One of those being priority registration for training grounds."

Shinsou was appalled. "How'd you manage that? It's only the fourth day of class."

Kai grinned. "Turns out my Quirk is a lot stronger than I thought, so I leveraged that—along with one of my inventions—to secure mentorship and a development studio for support gear. Pretty cool, right?"

Kai stepped out into the staff parking lot and walked toward a shuttle bus.

"Alright, lads, this is the bus that will take us to Ground Gamma. Climb aboard."

Midoriya and Shinsou followed Kai onto the bus, taking in the scene. The bus was unremarkable at first glance, but they quickly noticed a few key details. At the wheel was a handsome man in his mid-twenties, dressed in a sharp suit with a scar running over his right eye. He gave them a brief nod as they entered.

At the back of the bus, nestled in his signature yellow sleeping bag, was none other than Eraserhead. The hero was completely out cold, snoring softly despite the otherwise quiet atmosphere.

"This is one of the surprises I've prepared," Kai continued, as they all settled into their seats. "For Shinsou, Eraserhead has agreed to teach you how to use his capture weapon in his free time."

Shinsou blinked, looking surprised but intrigued. "Wait, seriously? Eraserhead's gonna teach me?"

Kai nodded. "Yep. He's pretty picky about who he trains, but I managed to convince him. You've got the potential, and his style might suit you well. You're good at catching people off guard, so learning to use a capture weapon effectively could make you even more unpredictable."

Shinsou didn't seem sure how to feel, but the idea of learning the capture scarf from Eraserhead—a hero he respected—was enough to excite him. "I guess I'll give it a shot."

Midoriya, meanwhile, leaned over to Kai. "So, uh, what's the deal with the driver? He doesn't look like a regular staff member…"

"That, Izuku, is your surprise. If you can figure out who he is in the ten-minute car ride to the training ground, you get an excellent prize. If you don't, no harm. We're still doing the training."

Midoriya's eyes narrowed as he studied the driver more closely. "He doesn't look like anyone I know. He's got a certain vibe to him, though…"

"Take your time," Kai encouraged, leaning back in his seat.

Midoriya devolved into a full-on mutter storm, pulling a notebook out of god-knows-where. Kai turned to Shinsou and struck up a conversation on something he'd been curious about.

"So how have heroics classes been? You guys do anything interesting?" Kai asked, wondering if his knowledge of canon was intact.

"Pretty good." Shinsou said. "The first heroics class we had 2v2 matches. The situation was that one set were heroes, one was villains. The heroes had to defuse a bomb; the villains had to defend it…"

Shinsou explained the entire first heroics class, with subtle prompting from Kai. It seemed to go the same as canon, with one key difference: Midoriya had managed to trash Bakugou before resorting to breaking his arms. Apparently, the training they had done had paid off—Midoriya could now limit himself to pushing only 5% to his limbs.

Before Shinsou could respond, Midoriya spoke up from the other side of the bus, looking excited. "I got it! I figured it out!"

Kai raised an eyebrow, glancing over at the energized Izuku. "You've got it? Who do you think the driver is?"

"Well, I originally ruled it out, because no way, right? But I kept coming back to it. I mean, you wouldn't give me an impossible test, so it must be someone I'd be aware of. If they're driving a bus on U.A. Property, they should be properly insured, so they have to be either a student or a staff member. He's too old to be a student here, unless he's from the Villain Rehab Program, but there are only five people in that program, and I know who they all are."

Kai leaned forward, intrigued, and the driver smiled into his rearview mirror.

"The only possible answer is that the person driving the bus is the Principal of U.A, Nezu." Midoriya leaned back in his chair, releasing a breath he'd been holding. "The question is, why is he a human? Isn't the principal non-human? His epithet is the Chimera Hero."

Kai grinned. "Nice job, Izuku. You've got it."

Nezu's smile widened as he glanced back at Midoriya. "Correct. And as promised, you'll receive your prize."

Midoriya blinked, still processing. "But… why are you disguised as a human? Aren't you supposed to be a… a chimera?"

Nezu's eyes sparkled with amusement. "Sometimes I enjoy blending in. It gives me a different perspective, and I find it... entertaining. Besides, there's no harm in a little fun now and then."

Kai chuckled. "See, I told you I wouldn't give you an impossible test."

Midoriya still seemed awestruck. "So... what now?"

Nezu spoke up before Kai could answer, his tone light. "Your reward for figuring it out is simple. You'll be training with someone today—someone special."

Midoriya looked confused. "Special? Who?"

Nezu merely smiled as the bus pulled up to their destination. "You'll see. Prepare yourself."

Kai led them off the bus and toward the training ground. As they approached a section of the facility, they saw Recovery Girl talking to another person. Kai gestured to the figure standing off in the distance. "This is your surprise."

Midoriya looked over at the person Kai was pointing at and saw a squat, elderly man. He had a scruffy white beard wrapping around his chin, and a black domino mask took up most of his face. He was wearing what looked like a child-sized hero costume, the jumpsuit being a light beige with puffy yellow boots and arm guards. He was wearing an oversized yellow cape and wielding a wooden cane.

Nezu spoke up. "Izuku Midoriya, I'd like to introduce you to Gran Torino, All Might's mentor. He'll be helping you with your quirk training."

Kai followed up, "That's right. Today, I've arranged for both of you to receive guidance from specialized teachers to better master your abilities. They've agreed to mentor you long-term, like a mentorship program."

Midoriya's eyes welled up with tears. "I—I don't know how I'll ever repay your kindness, Kai. You've gone this far for someone like me… It means the world. You're a true friend."

Shinsou, though trying to stay composed, had tears at the corners of his eyes as he nodded along with Midoriya.

Kai scratched the back of his head, looking sheepish. "Chill, bro. It's not that deep. Aizawa was already planning to train Shinsou personally after the Sports Festival. I just moved up the timeline. As for Gran Torino, he reached out to Nezu himself about mentoring you—something about some guy named Toshi being an idiot. I figured since we were doing quirk testing anyway, I'd invite him along."

Kai finished his explanation, but it didn't help. Midoriya was still watching him almost reverently.

Nezu clapped to clear the weird air. "Alright students, we're going to break off into pairs, Recovery Girl will assist when needed."

"Yes sir!" Kai, Shinsou and Midoriya said at the same time.

Kai and Nezu walked off into the Labyrinth of Pipes, making sure they were out of earshot.

As they walked, Nezu started talking. "That Midoriya boy is very interesting. If situations were different, I would have claimed him as my own apprentice, but then I wouldn't have found you."

"I'm flattered sir." Kai said. "The reason I wanted you here today was twofold. Reason number one was to meet them, I truly believe they will be the future of heroics. More specifically, I see Midoriya becoming a symbol like All Might, and Shinsou becoming a paragon of the underground like Eraserhead."

"I see where you're coming from." Nezu agreed. "The Midoriya boy has the heart of a hero. Not sure that Shinsou boy can follow in Shota's footsteps. I guess we'll figure it out as he goes, won't we? What was the second thing you wanted to talk to me about?"

Kai's expression turned more uncertain. "I feel another Devil Fruit building." He paused, trying to find the right words. "The problem is... I can feel the energy splitting. It's happened before, with the Kanga Fruit. It's like I have two different paths the energy can take, but I have to pick one. Does that make sense?"

Nezu's ears perked up, his excitement obvious. "Not at all!" he exclaimed with a grin. "But then, things like this are entirely intuitive to the user. No explanation you give will make sense to anyone else. That said, what are the options?"

Kai reached into his pocket and opened his inventory, grabbing the advantage ticket. As he pulled it out, A wheel shimmered into place in front of him and he chanted 'spin' in his head. As the wheel spun, he made sure to twist his expression into a concentrated look, like he was studying the energy deep inside himself.

After like ten seconds, the wheel stopped.

[Congrats! You've Pulled the Warrior Warrior Fruit!]

Type: Paramecia

Details: This Devil Fruit grants the user the ability to transform into and control the essence of a warrior spirit. The user can manifest as a ghostly, ethereal warrior made of energy, with abilities based on various forms of combat. The user can summon spectral weaponry and warriors.

OR;

[Congrats! You've Pulled the Puzzle Puzzle Fruit!]

Type: Paramecia

Details: This Devil Fruit allows the user to transform any object or even living beings into complex, puzzle-like structures. The user can manipulate the shape, form, and even the functionality of these objects, turning them into intricate pieces that can be reassembled however they choose.

"These fruits are really strong," Kai said, his voice filled with awe. "The first one embodies the 'Warrior Spirit,' allowing the user to transform into a ghostly combatant with the ability to summon spectral weaponry and warriors to fight for them."

Nezu took a moment to process the information, his brow furrowing in thought. "Hmm, sounds like a powerful one. What's the second?"

"The second one is the Puzzle Puzzle Fruit," Kai continued. "It lets the user turn anything they touch, even themselves, into a puzzle. From what I can tell, they can reassemble anything they've 'puzzled' into any configuration they choose. The possibilities are vast."