Ten years have passed since the death of Hoshino Ai, who was your blood mother. You and your twin brother and sister Hoshino Ruby and Hoshino Aqua are currently in high school and you are 16 years old. Ruby has become a Japanese idol and is constantly at the training of her B-Komachi group, and Aqua is constantly disappearing somewhere outside the house. Your brother and sister often return in the deep evening. And you sit quietly at home with your foster mother and do your own business.