MidoriIkaru
Izuku Midoriya was supposed to die in a plane crash when he was seven.
Instead, he woke up on a deserted island with fox ears, five tails, and a Quirk that turned him into something closer to a myth than a kid. Years passed. The other survivors disappeared. The animals listened to him. The island became his territory.
Then a group of pro heroes showed up and found the "feral child" who had been ruling the place.
Now Izuku is eighteen, looks eight, and is about to enter U.A. Academy of Heroics. He doesn't understand half of hero society, has zero filter, and treats the entire school like it's just another territory to explore.
Also, he decided the strongest rabbit hero in Japan is his mate.
Hero society has absolutely no idea what to do with the Five-Tailed Problem Child.