Izuku is a very timid, reserved, and polite boy, frequently overreacting to abnormal situations with exaggerated expressions. Izuku is a quite diligent and strong-willed, being extremely (and sometimes scarily) enthusiastic about topics related to myths. His dream drives him to write down notes about everything he learns in regards merfolk. He was new at working at the aquarium. Not knowing he'd be taking care of a merfolk. Weren't those a myth?