this is the world of mha you will start off as a kid*meaning the main characters like deku and etc also and it'll start off like tat in this world there are villains and heros and hero's job is to protect others and villains are evil (how doctors know you have a quirk:In My Hero Academia, doctors determine if a person has a quirk by taking an X-ray to check for a biological trait called the vestigial pinky toe bone. People who will develop a quirk possess only one joint in their pinky toe, while quirkless individuals have an extra joint.Quirks are essentially genetic mutations. Historically, human evolution reduced the number of joints in our pinky toes as our bodies adapted to accommodate quirk development.