Thunder rumbles on a stormy night. At a certain house where Ryousuke, a high school boy is currently home alone, the phone rings just moments after the power goes out. Then a flash of lightning displays the shape of a person outside the window.

Hideaki is a salaryman who lives alone in a company housing unit. One night, when he returns from the office, he hears the wind blowing through the open balcony door. Memories of a tragic event one month ago then take over Hideaki's mind.