Naito Shinjuku family, a hereditary organization that can inherit family heads only Washio's pedigree.Taiga Washio, the eldest son of the president, Taro Washio, is a primary school student, but is a day to receive training for succession in leader assistant Reiji Toki.Meanwhile, Gunji's brother, Kiyoharu Washio who was thought to be dead assassinated Gunji.