Toshinori Yagi didn't know immediately that something was wrong, as despite being the Number One Hero to Ever Exist™, he was rather unobservant at times. But eventually, the reality of the situation came around after trying to beat through his skull for several long months.
His quirk was fading.
Not in the way that his body was slowly growing more and more frail, because that he was painfully aware of. Nothing quite hurts more than having children start crying in fear at the very sight of you. He did not cry in a Denny's parking lot that night and you cannot prove it.
But more in the way that his kicks only caused large gusts of wind when he curbstomped a purse-snatcher through said curb instead of a weather-changing blow, and when he had to start straining more and more to achieve the feats he once pulled off so easily.
However, this alone was not enough to convince him, but it actually took One for All itself to basically tell him that the quirk had been passed on, but he was still trying to decipher the advice he had been given.
Inside of One for All:
"Why is my quirk fading? Did I somehow spring a leak in the power?" Toshinori asked desperately, practically pleading in the mysterious shadow realm he found himself in. He had never seen this place before, but it felt oddly familiar. Also he was on fire. Did he forget to mention he was on fire?
Anyways, after this statement, the collected vestiges looked around at the others, each attempting to hold in laughter as they silently pleaded for someone else to tell him. After a long, agonizing few seconds, the First user sighed, biting the bullet as he stood up to face All Might, walking up to him and putting a hand on his shoulder.
"Look kiddo, to put it simply, you passed on One for All-don't interrupt!" He interrupted, putting a interrupting finger in Toshinori's face who had been about to interrupt. "And regarding what you should do now?" The vestige let out a chuckle, slowly going maniacal.
"Skill issue." The vestige said, vibe-checking All Might out of the dream and back into his bed, where he awakened with a manly shout of annoyance. Meanwhile, the neighbors began calling the police regarding the shrill shriek of a young girl they had just heard, leading them to believe a child was being held captive.
The Symbol of Peace had rapidly written down everything he had heard and seen, having to help redirect some friendly officers who were looking for some poor girl, and trying to decipher what the First had told him.
When he couldn't figure it out, he sent it out to Nezu, who owed him a favor. For this, he was immediately blocked and he couldn't figure out for the life of him why.
Maybe the First gave me something inconclusive because I couldn't stomach the truth? Toshinori thought idly, pen twirling at somewhere close to Mach 3 in his fingers, Well, it's not like I can stomach anything so the phrase doesn't really work now that I think about it. I can't pancreas it? No, that sounds weird…how about I can't…liver it? No, it still doesn't work…I can't heart it! Toshinori snapped in revelation, ending the unfortunate twirling pens life, ink splattering all over his hand as he completely did not notice a thing. The First gave me something inconclusive because I can't heart it!
He nodded in assertion, confident that he had finally figured out the solution he had been looking for. Yagi blinked, "Where'd all this ink come from? And where'd the pen go?!" He shouted, once more hearing faint laughter that seemingly came from inside of his head.
Izuku Midoriya hummed a tune he wasn't sure he had heard before as he sat atop a massive, teetering trash pile that would've made Newton violate the Geneva Convention, idly scribbling down various training plans he should use for trying to get into the UA hero course.
"Karate? Don't have a Mr. Miyagi to train me. Swordplay? More like self-dismembermentplay. Somehow gain a mysterious quirk, cultivated over two hundred years to duke it out against a two centuries old megalomaniac, be trained by the Number One Hero and become the greatest hero of all time and somehow still get beaten out by a suicide-baiter in popularity polls?" Midoriya paused, the gears in his head grinding to a halt as he re-read what he just wrote, "What the fuck?"
He was just about to give up on this whole idea and climb down the Newtonian Nuance when the voices in his head popped up in his psyche, 'Maybe you can clean the beach to strengthen your body?' Izuku stopped, writing down the option and nodding briefly. "Huh, thanks to the mysterious voices in my head that suddenly appeared a few weeks ago." Considering for a moment more, he erased schizophrenia medication from his to-do list, and Izuku could have sworn he heard a relieved sigh in his head.
