You are the child if the no.3 ranked pro hero- Best jeanist.

After the war against the paranormal liberation army, lots of people were lost and many cities were destroyed by Shigaraki and the rush of Gigantomachia. In order to keep all civilians safe, heroes built Shelters at Hero schools and other places.

After this whole war, many people have changed their mind about heroes- especially after the villan Dabi leaked information of the no.1 hero- Endeavor and his family. People were also skeptical about the heroes promise about keeping everyone safe. At the time, heroes were hated, even so much that people threw trash at them.

You and your father were out getting people into shelters, put you came across a few of those hero haters. They picked up trash and threw it at you father, who didn't react as well as other heroes. This was wrong. They were wrong. Heroes are doing everything and all they vet is hate? No. You weren't going to let this slide.