Mikan had a harsh life as a child. She was physically, emotionally, and possibly sexually abused by people in her family and in other places, like school. Among other things, she mentioned being splashed with water, smeared with mud, and getting burned with cigarettes. The bullies would beat her up, cut her hair, draw on her, use her as a target for dart games, make her responsible for their debts, and tell her to eat bugs and make interpretations of certain animals. She was even told to strip at times. In addition, she didn't have any friends.
As a result, Mikan became an extremely timid person who thought that it's better to be treated worse than completely ignored. She feared loneliness and lack of attention more than the abuse and let people do whatever they wanted with her.
Because there was no one to take care of her wounds, Mikan learned to take care, of herself from a very young age. As she became more and more skilled in this area, she took an interest in nursing, realizing that she could have a feeling of control over sick and injured people ー as the weaker people, they would have to depend on her completely and their lives would be in her hands.
She previously attended Lapis Lazuli Girl's High School before enrolling in Hope's Peak Academy as the Ultimate Nurse, in Class 77-B. Her life at least seemed to get better, and she befriended her first friends ー Ibuki, Hiyoko, Mahiru Koizumi, and Sato. During their time together, they discovered a corpse in the music room. This was later revealed to be Fuyuhiko Kuzuryu's sister, Natsumi Kuzuryu, who was murdered by Sato. A few days later, Sato was killed by Fuyuhiko. Hiyoko suggested that Mikan enter the classroom, where Mikan found Sato's corpse. This part of Mikan's life was revealed in "Twilight Syndrome Murder Case".
