Twitch: you are my toy (2004)

Minori is a head-strong photographer who is romantically involved with Kushida, her editor. On a photography assignment she gets into an argument with her subject, Ageha, a female erotic manga artist who, like Minori, is 30 and single. Shin'ichi, the journalist on the assignment, receives most of the blame for the failure of the project. Minori sleeps with Shin'ichi, then discovers that her own position is not as secure as she thought, when she suspects that Kushida is also involved with Ageha. The series of events causes Minori to reconsider her own lifestyle.