A high school student who suddenly moved in to Ochiai Kouta's house to act as his older sister while his father is away. The reasons are unknown except for the fact that she owes him for the ice cream. She seems to be a great fighter, as she beat up three bullies and a thief. She is immature, but in the end helps Kouta find a solution to his problems. She is a bit of a mystery, as Kouta knows nothing about her.