Domestic na Kanojo

Synopsis

Natsuo and Hina are mistaken for a couple at a restaurant. They talk at a beach, Natsuo being curious about why she had the affair with Shuu; a flashback shows Hina's high school days with him. Natsuo tells Hina that he has finished his novel, and confesses his love for her. He is surprised when she asks if they can go out; she wades into the water with him, explaining that it would be like committing double suicide because they would lose everything. They return home and Hina reads Natsuo's novel. The following night, Natsuo peeks into Hina's room and sees her masturbating while calling Shuu's name. He drops a book and hides behind the stairs when she looks for what caused the noise. The next morning, Hina greets Natsuo and says that he should wake up a little early; she waves to him as she leaves; looking at her hand, Natsuo feels embarrassed.

(Source: Wikipedia)