The rest of the week passed quickly, and it was soon time for Izuku to return home.

"You did well during your time here. With how well your progress is going, it won't be long before you're able to fully control One For All." Tony said. "You still have a way to go, but you're getting there."

Izuku nodded. "Thanks, Dad."

Tony looked pretty grim as he thought of something.

"Listen, Toshi will have something important to tell you when you get back to UA. It's very important, so make sure to pay attention."

"Something important..." Izuku muttered. "I wonder what it could be."

The students of Class 1-A were all animatedly chatting with each other about their internships.

"Man, talk about an awesome week!" Sero said.

Katsuki smirked. "I actually got to be in the thick of it at Hosu!"

"Man, you wound up there?" Eijirou asked. "With me, it was mostly refining my Quirk into a style that was suited to my personality."

"I feel like I can do so much more with my Quirk now! Learning with Swampanne was the best choice ever for me!" Mina said.

"I actually got to help out with a hostage situation," Kyouka said.

"I was able to help deal with some villains, too. We were taking down a group of drug smugglers that were posing as stowaways." Tsuyu said.

Fumikage nodded. "It appears we all had fulfilling internships."

"Hey, how were things between you and Asahi-Sensei, Uraraka?" Morimoto asked.

"It was very enlightening..." Ochako said, having a battle aura around her.

"Damn, woman are a whole lot fiercer than I ever was led to believe..." Minoru muttered nervously.

"Still, I think the real stars have to be Midoriya, Iida, Todoroki, and Shudai!" Denki said.

"Still wish I could've been there!" Katsuki grumped.

"So what was Stain like in person?" Sero asked.

"He's rather difficult to describe. His tenacity is certainly to be admired, and his motives are understandable." Tenya admitted. "The trouble is he's fanatical, narrow-minded, tunnel-visioned, and completely out of touch with how the world works. Not to mention, while he wanted to change the world, he did so through cold-blooded murder. Such actions cannot be condoned under any circumstances."

"Honestly, he was just a rabid All-Might fanboy," Tsumi said. "Pretty soon, the whole world will forget him."

Izuku cleared his throat. "All this talk is good, but class is about to start. Let's take our seats, everyone."

Later, the class was out in the industrial simulation with All-Might. Tenya's costume had been successfully repaired, and the whole class was suited up.

"Good to see everyone had a productive internship! Now's the time to put that learning into practice! We're going to have a little race across the industrial zone." The Symbol of Peace announced. "Now this is rescue training, but it's a little different than the disaster training you had at the USJ."

He brought up a nearby holo-screen.

"You'll be competing in groups of six, with each student having a different starting location on the outskirts. The interior is like a maze, and your only means of navigation will be a distress signal I'll be broadcasting from the center of the zone. The first one to reach my location, a simulation of a citizen seeking aid, will be the winner. Try to keep property damage to a minimum. This means you, Young Bakugo."

"Aww screw you guys!" Katsuki snapped as everyone else snickered at his expense.

The first group was Izuku, Mayumi, Oujiro, Tenya, Sero, and Mina.

"All six of them have good mobility options, especially Sero, Goto, and Midoriya." Momo noted.

"Wanna take bets on who's gonna make it first?" Eijirou asked.

"Deku hands down," Katsuki declared.

"I got good odds on Oujiro," Denki decided.

"I'm betting on Sero," Eijirou said.

"My money's on Ashido!" Minoru said. "And no, it's not just because of her hot athletic body...but I'd be lying if that wasn't part of it."

"Give Goto some credit, okay?" Kyouka said.

"I think Iida might be able to take it. He is incredibly fast, after all." Ochako suggested.

All-Might held up the distress beacon.

"And... BEGIN!"

As expected, Sero and Izuku took to the air using their special skills. Tenya raced through the lower parts, Mina skated along some of the pipes, and Oujiro kept slamming his tail against the various roofs to leap from building to building.

Mayumi activated her Tape Buster, which she used to mimic Sero's moves to keep up with him and Izuku.

"This is gonna be a breeze!" Sero bragged. "It's like this course was made for me!"

"Don't count on it!" Izuku called out, quickly racing past him.

"And you know what they say; imitation is the highest form of flattery!" Mayumi pointed out, swinging beside Sero.

Izuku was doing well, but wound up slipping on a pipe. However, instead of just falling, he suddenly found himself floating in midair.

Everyone watching looked at Ochako in shock.

"Don't look at me! I might have gotten stronger, but I still need to touch something to activate my Quirk!"

"Are you saying that this shit is all Deku...?" Katsuki asked.

"So...seems Izuku unlocked another of OFA's piggybacked Quirks," Ben noted.

With this new ability, Izuku was able to recover and reach All-Might first after regaining his bearings, completely shocking him, and not for the obvious reason.

"One For All chooses now of all times for Young Midoriya to unlock Nana's Quirk, Float?"

He shook his head to clear his thoughts and provided Izuku with the winner's sash.

"That was a tight race. Compared to the start of the year, you've all shown great improvement."

"Where did that even come from, Midoriya?" Sero asked in surprise. "You were just floating in midair all of a sudden!"

"I believe Midoriya was able to reactively adapt his body to make himself lighter than air to avoid falling." Tenya chimed in, providing the perfect cover story.

"Saved by Iida..." Izuku sighed internally.

The boys got changed in the locker rooms.

"Man, I may be better at using my Quirk now, but it's still not that great for mobility." Denki said.

"Don't sell yourself short, Kaminari. Considering you have enough control to propel yourself in the air now, it shows just how much of your power you have mastered." Fumikage said.

Minoru discovered something behind a poster on the wall.

"Holy crap! I think this hole leads right into the girls' locker room next door. A present from previous generations passed down to our humble hands...!"

He took a quick peek while mumbling about each girl's unique beauty, only to get one of Kyouka's jacks in his eye through the hole.

"What did you think was going to happen?" Morimoto dryly pointed out.

"I think only Shudai would be comfortable with you peeping on her." Ben joked. "She's your kind of freaky, after all."

After class, Izuku, Ben, Morimoto, Mayumi, Katsuki, Tenya, and Ochako were invited into the teacher's lounge by Toshinori.

"Is everything alright, Yagi-Sensei?" Tenya asked. "You seem more solemn than usual."

"To be perfectly frank, Young Iida, no, I recently learned something that troubles me greatly," Toshinori admitted. "Young Midoriya, I heard that the Hero Killer swallowed some of your blood. Do you remember what I said when I gave my power to you?"

"EAT THIS!" Izuku recited, in an almost perfect imitation of All-Might.

Everyone was flummoxed at the sudden joke, but very quickly burst into collective laughter. Once everyone calmed down, Izuku got serious.

"You said that it's important to have a recipient ingest your DNA, but that you also need to want to pass the power on. Actually, I had no intention of passing on One For All at the time, especially when I don't even have full control over it, so there's no chance it'll wind up in Stain's hands."

Toshinori nodded. "Exactly. One For All isn't something that can just be taken by force. The name itself has a double meaning. First, it's a reference to the saying, 'One for all, and all for one, and heaven bless the land.' Second, the name refers to how the Quirk works. One Quirk, for all people."

"So what does all this have to do with Stain getting a taste of Deku's blood?" Katsuki asked.

"That, Young Bakugo, is the reason why I'm telling you all this. It has to do with the origin of One For All." Toshinori explained. "It wasn't made like other Quirks. It didn't spring up into existence out of the blue like some others. In a way... One For All was engineered."

"Who could have engineered such a Quirk? And how could a Quirk be engineered?" Tenya asked.

"The reasoning goes back to the dawn of Quirks. I'm sure you know the story, how it all started with a young baby in Qing Qing, China, who suddenly gained the ability to become luminescent." Toshinori explained. "In those days, there was chaos. And out of the chaos suddenly came a different sort of Quirk. If there's a One For All... Then, naturally, there would be an All For One, its exact opposite. All Quirks, for one man."

"So it's a Quirk that can steal other Quirks. The user taking them for himself." Ochako realized.

"Well, he could if he wanted to, but he could also give the Quirks to someone else. It was even possible for him to return a Quirk he had taken to its original user." Toshinori clarified. "The user of All For One, no one really remembers his name anymore, took advantage of the fact that during his youth, anomalies were cropping up in great numbers, making it impossible to say what was normal anymore. Laws and human rights were hotly debated, and civilization's progress stalled."

"I did hear some analysts claim that without anomalies triggering in our society, we could have easily had accessible space travel by now." Mayumi noted.

Toshinori nodded. "Yeah. All For One, the man who owned the Quirk in question, rallied many people together. He was a student of the first supervillain, Crimson Death. At first, he worked to quell the chaos for his own benefit. He took Quirks from people who didn't want them, and gave them to people who did. All in exchange for favors. Some Quirks he kept for himself. He also used a vast information network to find Objects of Power and sold them to the highest bidder. Before long, he had total rule over Japan's criminal underworld."

"But none of this was ever brought up in history," Tenya pointed out.

"Neither is One For All, and that certainly exists." Ben pointed out.

"The past involving All For One is seen as a shameful moment in our history," Toshinori clarified. "Anyway, when a person gains true power, they enjoy showing it off. All For One's power went to his head, and he started to pull away from his master to commit evil for his own sake."

"So how does this relate to One For All?" Katsuki asked.

"There were many people who couldn't bear the burden of the Quirks they were given. They became mindless living dolls, incapable of speaking." Toshinori explained.

Ochako gasped. "The Nomus..."

Toshinori nodded. "Conversely, some powers evolved as they moved on, or combined with other power sets. Now, this evil man had a younger brother who was Quirkless. Unlike his brother, he had no intention of being evil. In fact, he had a strong sense of justice. It pained him to see his brother's evil deeds, and he kept resisting him. For some reason, All For One decided to transfer a Quirk to his younger brother, one that would allow him to stockpile power over time."

"Stockpile power..." Izuku realized. "You mean..."

"It turns out the brother wasn't actually Quirkless, but on its own, his Quirk was useless. It simply allowed him to pass on Quirks." Toshinori finished. "The two Quirks merged together in the younger brother's body. This created a new power. That is the true origin of One For All."

"Sick..." Ben muttered.

Toshinori chuckled mirthlessly. "Ironic, isn't it? How the power of the Symbol of Peace could come from the ultimate force of evil? Justice often tends to spawn from evil, like two sides of the same coin."

"But hold on; if All For One is as old as you say, shouldn't he be dead by now?" Morimoto asked.

"You'd think that, but for one who can steal Quirks, the sky's the limit. More than likely, All For One has access to Quirks that can lengthen one's life. And with combat being what it was at the time, this Symbol of Evil seemed almost immortal." Toshinori clarified. "So the younger brother, calling himself One For All, decided to pass on his power. First, he sought out someone who could make him stronger. Then, when the time was right, he passed on One For All to that man."

"He wanted to make One For All strong enough to defeat his brother," Ochako realized.

"That he did. The man he sought out knew an ancient spiritual technique that let him speak with and train alongside his ancestors. This very technique merged with One For All when he inherited it to allow future users to speak with their predecessors. He eventually passed on One For All to his own apprentice, and so on."

"So in a way, One For All has some kind of soul magic added to it as well," Ben noted.

Toshinori nodded before growing sad.

"Each of us has fought All For One at some point. Thus far, only my sensei and predecessor, Nana Shimura, died by his hand, though up until me, none of the others were able to truly defeat him, only beat him back temporarily."

"Did you say Nana Shimura? The hero Nimbus?" Mayumi asked. "I remember Dr. Light talking about her before."

"She made a crucial mistake when she faced All For One; she fell for his taunts," Toshinori said. "He had murdered her husband, tricking her into fighting him on her own, something no other One For All user did. Especially not me, when I learned what had happened. I fought him five years ago, alongside Endo Hound, Serpenshia, Depestilous, Regenizard, Bang Silverfang, and Blast. It was a dangerous fight, and my friends knew that one wrong move and they'd lose their Quirks. Still, they fought, and in the end, they succeeded in making the perfect opening for me."

"Awesome!" Katsuki grinned. "I knew you wouldn't lose to that creep."

Toshinori nodded with a chuckle before tenderly touching the spot where his scar was.

"This old injury was the only collateral. It was a miracle. But All For One wasn't as finished as we thought. The attacks on both the USJ and Hosu proved that. He was the one who was the brainchild behind the League of Villains. But while he is a threat, he probably doesn't have as much agency as he used to. If Sin Scholar is working with the League, then he and the rest of the Crimson Council are likely taking control. Or they might be training Shigaraki so that he can lead."

"So I might have to fight All For One someday," Izuku realized.

"Wonderful, it wouldn't be a young next generation hero story without having to fight an ancient supervillain!" Ben said in exasperation, throwing his hands in the air.

"Hey, you're not fighting that creep alone, Deku!" Katsuki pointed out. "If All-Might's friends can help him, we can help you!"

"Plus, the guy's gotta be on life support right now. He may still be dangerous, but there's no way he's as strong as he used to be." Morimoto added.

"Indeed, All For One is certainly not going to be an easy fight. But he only survived against me by the skin of his teeth. Once you're able to access everything One For All has to offer, I've no doubt you might be able to succeed where I failed." Toshinori said. "However... I won't be able to fight with you. One For All is yours now. I'm just using the leftover embers. It should last me a while, long enough to finish teaching you. But this fight is now for the younger generation. My time is soon to pass..."

Izuku nodded in understanding as he and his friends headed off. Unbeknownst to them, Tsumi and Akatani were eavesdropping at different points.

"C-Could they be the ones to beat HIM?"

"I'm looking forward to what you guys do."

The next day, Aizawa had an announcement to make to his class.

"Summer vacation is coming up. But you won't have time to relax. You'll be given training at a special summer camp. This is going to be important for you, since it will allow you to experience in variable terrain. However... Those of you who don't pass the final exam... Will not be going."

"Another of his 'logical ruses'," Izuku noted to himself. "Training like this is too important. No... He just wants us to study harder for the final exam."

Meanwhile, in a large tower building, Dr. Ujiko and Gustav were checking on All For One's life support.

"I wasn't expecting the Hero Killer to be caught. Especially not in such a way that his ideals were shattered." All For One admitted. "If not for my old comrades in the council, Tomura wouldn't be able to gather needed allies for the true League of Villains."

"Aren't you concerned?" Gustav asked. "Tomura is leaning more towards the Council, after all."

"I don't know what Master has in mind regarding them, but I'm sure I can overcome it. If I was able to survive a battle with All-Might, then nothing could possibly bring me down for good." All For One said. "Those children had better enjoy their transient peace while it lasts..."

Ujiko sighed. "A shame Midoriya has One For All. Such a potent Quirk like his Reactive Adaptation would bring your body to its full potential again, allowing you to take control more easily."

"Nothing to be done about that. Besides, the Council will certainly be able to help Tomura unite the villains seeking us out. Of that, at least, I can be certain." All For One said.

The Symbol of Evil gave a malevolent chuckle as he leaned back in his chair.

"One way or another... I'll make sure that twisted mind is used to become the next me..."

Up next will be the Final Exams! Strap yourselves in, it's gonna be a long one!

-BIO TIME-

[MUGEN SHIGARAKI/ALL FOR ONE]

Quirk: All For One

Quirk Description: All For One allows the eponymous user to steal Quirks from anyone he touches for personal use or transfer the stolen Quirks to anyone. It also allows him to wield several Quirks simultaneously. Giving and taking away Quirks is done through touch, through holes in the palm of his hands, once they come into contact. All For One can be used to combine several Quirks to create devastating techniques, which would typically not be possible with the usage of only one Quirk. Furthermore, it can also be used to help restrict a Quirk's drawbacks and weaknesses through the usage of other Quirks, allowing Mugen to easily handle multiple powers without facing repercussions to his body.

[KYUDAI GARAKI/DARUMA UJIKO]

Quirk: Life Force

Quirk Description: Life Force allows Ujiko to double his life span, causing him to age at a slower rate, making him look much younger than he actually is. This Quirk comes at the cost of sacrificing physical mobility.