Natsuki Hagiwara

Age 17, High School student. Suddenly moved in to Ochiai Kouta 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. On later chapters, it is reveled that she ran away from home because her elder sister is forcing her to be one of her lingerie models and is also pimping her to be some rich old man's mistress.