“It’s not a quirk,” Izuku tells the poor sod, who looks like he needs to catch up on four years of sleep and has been combating that fact with caffeine pills and spite alone. “It’s breathing. I’m literally just breathing. Do you want me to stop breathing?” he demands. When Eraserhead glares at him like he’s murdered someone (which he has, technically, but what is someone, really), Izuku sniffs righteously and says, “Stop glaring at me!” Eraserhead takes a deep breath. “Breathing, yes, like that,” Izuku says eagerly. “Want to see me do it too?” “No,” says Eraserhead. Midoriya Izuku's family tree may or may not include one Kamado Tanjirou.