Years ago, following the death of his parents, Yuuji Enomoto was adopted by the family of his childhood friends, the twins Yuna and Nina Tsubakihara, and their mother Mira. Now a high school student known as Yuuji Tsubakihara, he shares a home with the cute twin sisters and their attractive mother. While the shy, reserved Yuna and the outgoing, talented Nina are his family, Yuuji gives in to his desires after seeing Yuna reject a confession. As Yuuji and Yuna finally consummate their lifelong love, can Nina and Mira stand idly by?