Determined to die (Undertale x My hero academia x male reader crossover)

Y/N was born quirk less. And he was bullied relentlessly for it. He got so fed up that he declared to his bullies that he would climb mt. Ebott to prove he is brave. What he doesn't know is what awaits him, and falls to the underground. He is attacked by flowey and goes into panic, killing everyone in the underground, and being fused to chara. Feeling bad, he resets and frees all of the monsters. He then discovers something about himself. He developed a quirk in the underground, and it is much more powerful than it seems