Yoko Kan is Taisukes older sister. She works at his school as the nurse and often treats her brother mostly because of his fights. After the death of their parents Yoko has to take care of her brother. She earns the money and pays for her brothers schooling. She makes Taisuke clean and cook for her as she says that she gets the money so he has to do chores. She is a very confident older sister that trusts her younger brother.