Chikan densha: OL ai to seiyoku no hibi

Yoko is an office worker at a small transport company. The driver, Shuji, has feelings for her, but Yoko has no desire to fall in love with a man. Yoko pretends to be plain at work, but at night she sometimes puts on makeup and goes to hotels with men. However, she only sleeps with each man once. It was just an act to satisfy her lust. Then she receives a strange phone call, and finds out that someone is always watching her. Who could it be?