Natsuo Fujii (voiced by Taku Yashiro) lost his mother when he was young, so he was full of longing for older women. By chance, Natsuo met the English teacher Tachibana Haruna (voiced by Hikasa Yoko) on the roof of the school. Haruna's gentle figure deeply attracted Natsuo and made him fall in love unconsciously. However, Natsuo knew that it was impossible for him and the teacher to have a result, so he vented his depression in the social activities. At the social gathering, Natsuo met a girl named Rui (voiced by Uchida Maaya). That day, Rui gave her first time to Natsuo. Afterwards, Natsuo's father told him that he was about to remarry, and the woman was going to bring her two daughters to live in Natsuo's home. What Natsuo didn't expect was that the two girls were Haruna and Rui.