For 5 years, Otome and Minami have been step siblings. Their grandmother is staying with them, taking up Otome's room while she recovers from surgery. This results are to Otome having to bunk in her brother's room. They have divided the room with a sheet hanging from the ceiling between the bed where Otome sleeps and a futon on the floor where Minami is sleeping. This often results in Otome either falling half-dressed out of her bed and onto Minami or Minami knocking down the sheet while Otome isn't there and rifling through her things. Shortly afterwards, a boy named Amane kisses Otome and they begin to date. This sparks emotions in Minami, forcing him to realize that he may feel for Otome more than brotherly love. As Minami begins to express this inner struggle through teasing, harsh words, and awkward romantic gestures, Otome comes to feel the same things.