Test Subject #001

The league of villains wanted to make a weapon to kill All Might. They kidnapped a child at the age of 4 because he was quirkless. His name was Izuku Midoriya but is normally called Deku or subject I. They chose the name subject I because it was the beginning letter of his first name and the roman numeral for one. They give managed to give Izuku a mutation quirk which altered his genetic male up to resemble frogs'. Also, Aizawa is his guardian after rescuing him. He gets rescued after the entrance exam and slightly before USJ. He is a transfer student.

Or Izuku also has the quirk frog with more abilities from other animals.