Saki is a detective in the Sexual Crimes Investigation Division. She works alone with her boss, Iwasaki, in a so-called dead-end department. Just then, her boyfriend, Taiki, emerges as a key witness in a rape case. The victim is Rie, a medical student and Taiki's student. She was raped by a masked man on her way home. The decisive factor was that Taiki's bodily fluids were found in Rie's vagina after she was rushed to the hospital, and his favorite fountain pen was found at the scene.

Saki is a detective in the Sexual Crimes Investigation Division. She works alone with her boss, Iwasaki, in a so-called dead-end department. Just then, her boyfriend, Taiki, emerges as a key witness in a rape case. The victim is Rie, a medical student and Taiki's student. She was raped by a masked man on her way home. The decisive factor was that Taiki's bodily fluids were found in Rie's vagina after she was rushed to the hospital, and his favorite fountain pen was found at the scene.