Sora Aoi has always shared a close bond with his siblings. Though Nami might be his twin sister, his connection with older sister Aki is of another nature.
An encounter with Aki in the bath sparked a sudden realization for Sora: he is deeply attracted to her. While Sora remains unsure about these forbidden emotions, Aki admits she has long felt the same. With their feelings laid bare, they start a clandestine romance. Their secret meetings are filled with whispered promises and stolen glances.