Disclaimer: I don't own anything, but the story.
Chapter 3: The training begins!
Izuku was crying as Ash and Kurusu were checking their wounds, not sure what to make of the situation. "You are the one who's worthy to inherit my strength!" All Might said, getting looks from the three. "That expression is a gas!" All Might said, laughing. "It's just a 'suggestion', for now, listen, boy, your true test is just beginning!" All Might pointed at Izuku. "It's simply a matter of whether or not you'll try your damnedest to absorb my 'power'!" All Might started coughing up blood and quickly wiping it away.
"Wh-wh-wh-wh-what?" Ash and Kurusu stuttered.
"I'm talking about my Quirk, kids."
"That still doesn't clear anything up." Again, Ash and Kurusu said.
"You know that weekly magazine, 'Friday'?" All Might explained, getting nods from the three. "They had my Quirk down as just some generic boost of super strength. I always avoided the topic with some well-timed zingers whenever it came up, the reason I do that is because it wouldn't do if the 'Symbol of Peace' was not, in fact, a 'natural born hero'." The three were getting more and more confused. "My Quirk is a power, not unlike the 'Sacred Torch' of legend that is passed from one bearer to the next.
The three's jaws anime-dropped. "A Quirk... you can inherit!?" Izuku asked.
"That's right, kid and I tagged you as next in line." Kurusu almost passed out on the ground, when Ash caught him while Izuku was muttering to himself.
"It's certainly the case that the nature of All Might's Quirk is debated as one of the world's Seven Great Mysteries- Somedays I never see sunlight researching the matter on the Net- but a Quirk that is inherited?" Izuku muttered, quickly.
"Great, he's doing that creepy muttering thing." Kurusu thought, still hanging on to Ash.
"No, I'm afraid I can't wrap my mind around this fact, because recorded history has shown that everyone has their own individual, inborn traits which make up the fundamental factor by which they may establish, so a Quirk someone can inherit is immpossip-"
"Jeez, enough kid!" All Might said, waving a hand. "Don't immediately dismiss that possibility, that's a bunch of nonsense." Izuku was shocked, while Ash snikered.
"Right, in the Otaku pride." He thought, getting a punch in the arm by Kurusu.
"There's a lot I keep to my chest, but I don't tell lies!" All Might said. "It's the power to transfer power and the name of that vaunted ability to which I've been entrusted is none other than 'One For All'!"
"One... For All?" The three repeated amazed that such a thing existed. All might nodded then began to explain.
"One man cultivates the power, that man grants it to another and again it is fostered and passed down, in doing so brave hearts with unwavering calls to save lives can burden this might!"
"Why are you giving someone like me such an awesome power?" Izuku asked.
"Yeah, no offense, Izu-Chan, but you're kinda plain." Kurusu stated.
"I've been searching for a successor for ages and now I've found someone I wouldn't mind giving it to!" All Might said. "Because you, who, despite not having a Quirk and being a mere powerless fan of heroics, shined more than any of those other so-called 'Heroes'!" Izuku started wiping his eyes. "But hey, it's still your decision to make, of course, what do you say?" Izuku gave All Might a serious look.
"Yes, please..." He said, getting a laugh From All Might.
"Now that was a quick reply, as expected, you rascal."
"Hey, there's only one place to train new heroes and that Yuuei High." Kurusu stated.
"So if you're going, then we're coming to!" Ash said, smiling.
Two days later 6:00 A.M.
"Oh, my arm, oh, it hurts, ooohhhh..." Kimihito whined, clutching his arm.
"Cut it out, you big baby, I didn't even hit you that hard." Ash bluntly stated. Izuku was training with All Might, while Ash and Kimihito were at home, doing their own thing. "Remember what you said, I take the lead on the physical training, while you help me study, now get up." Ash taking a picture of Kimihito.
"Why are you taking a picture of my pain!" Kimihito yelled.
"All Might told me to, plus he already took one of me... after I was knocked out..." Ash pocketed his phone and got into a boxing stance. "Now, come on, we've got ten months until Yuuei's entrance exam." Kimihito looked at his twin and then to the folder on the chair, the one All Might gave them.
He sighed and got up. "All right, all right, you sadist..." Kimihito got into a defensive stance.
At school
"Oooohhhh, my muscles are screaming, I really shouldn't have agreed to this!" Kimihito though, clutching his side.
"Oooohhhh, my head, I really can't believe Kimihito made me study so much stuff." As thought, rubbing his head.
"Moreover, if I hustle with the garbage clean-up, I'll never make it, if it was just a section of yard, it'd be fine, but I have to do the whole she-bang, but this is all to train up a body that can pass those sorts of tests, this is the crash course of heroics!" Izuku muttered, getting looks from everyone, except Ash, Katsuki, and Kimihito. Izuku kept muttering, until their teacher extended his hand and hit Izuku on his head.
"Midoriya, if you've got time to mutter, then you've time to study, did that encounter with that villain mess you up in the head?" It went on for weeks, Ash, Izuku, and Kimihito sparred, trained and studied on a day-to-day basis. They ran, lifted weights, swam, study for night after night, went on extremely strict diets and threw up more than once.
Three months later
Ash was at the desk in his room studying math and science, his worst subjects. "If Izu-Chan can take this torture, then so can I." Kurusu, on the other hand, was lifting fifty pound weights, for ten sets of twenty.
"Come on, Kimihito, you said, you'd go to Yuuei with them, so you'd better damn well keep your word!" A woman was watching her sons, and couldn't help, but wonder what came over them. They kept training and training until...
Day of the exam, 6:00 A.M.
Kimihito was on his last set of bench-pressing eighty pounds, before getting up. "We've changed, you know?" Kimihito grabbed his towel and whipped off his sweat. "Look, ya see..." Kimihito looked and saw the picture Ash took. Kimihito looked at his full-body mirror and saw how different he looked. Kimihito was a foot and six inches taller and sported well-defined build with a six-pack. He looked at Ash, who didn't grow all that much, but was still as muscular as him.
"I feel like we cheated, I mean we got help from the No. 1 Hero in the world." Kurusu said, picking out a shirt.
"Naw, we're different, someone like us, you, me and, Izu-Chan had to bust our asses to get here, while guys like Kacchan are strutting about like they own the place."
"Ash-Chan, Hito-Chan, breakfast is ready!"
"Coming, Mom." They yelled.
"Ash, go... Put on a shirt already." Kimihito said, walking out the door. Ash looked at Kimihito's mirror and looked at where Kimihito was.
"Why am I still short?" Ash muttered to himself, before going to his room.