The protagonist, Hayato, comes from a single-mother family. Having been lovingly raised by his mother, Aina, Hayato has come to love Aina not as a mother but as a woman. But this mother is so cute that it's hard to believe she has a son! After a series of events, Hayato comes to mistakenly believe that Aina is actually his father's second wife and is hiding the fact that they are not related by blood. "Then surely it's fine if I confess?!" With Hayato's confession, the story begins to move...