Freshly arrived in Tokyo, Hiroko is hired mid-year and assigned to work in the general affairs department. One day, cleaning staff member Sugaura accidentally disposes of important meeting documents, forcing Hiroko to panic and stay late to fix the mistake. Upon learning this, Sugaura shows up in the general affairs office. Knowing that no one else is around, he begins approaching her—seemingly having had an interest in Hiroko for some time. Soon, Sugaura attacks her. Tension and anxiety escalate rapidly as the story plunges into intense depths.