While the husband is away on business, the Kiyono family lives with wife Fumie and their son Tatsuya. Fumie is worried about Tatsuya's shy and reserved personality and has always thought that she must do something about it. One day, Tatsuya brings a friend home, which is unusual for him. The friend introduces himself as Yoshino and is very polite. Fumie breathes a sigh of relief, feeling that Tatsuya has grown up. However, unaware that Yoshino may have a dark side, Fumie and Tatsuya fall right into his trap...