When Aizawa Arisu was in high school, her young father was in the hospital for treatment of a fatal disease. Although he was always smiling in front of his daughter, Arisu knew that he was worried about leaving her all alone in this world. To try to reassure him, Arisu asked his 26 year-old doctor, Ichinose Tatsuya, to pretend to be in a relationship with her. Suddenly, however, her father took a turn for the worse... Just when Arisu thought she couldn't take any more bad news, Dr. Tatsuya informed her of something else that proved to change her life forever.