When Kota Izumi was three, both of his parents were defending a village from the villain Muscular and they sacrificed themselves to save the civilians. The heroes' efforts were constantly praised by others, but it ended up scarring their only son, Kota.
The duo managed to injure Muscular enough to drive him away, destroying his left eye and leaving him with a deep physical scar.
It has been stated that they both had water-based Quirks.
They were able to cause a serious injury to a powerful A-rank Villain.