Atsushi is staying with his aunt Aya, whom he has admired since he was a child, while he is taking his exams. Atsushi is excited to be living alone with the sexy and gentle Aya, but Aya is feeling lonely as her husband never comes home. Aya's smile is getting fainter day by day. Atsushi is concerned about her lonely and fleeting smile, so he goes to check on her... and there he has an unforgettable experience.