In preparation for Children's Day, Jeongnam's school has decided to perform the story of Mr. Bang Jeong-hwan as a children's play as a school event, and is busy preparing for it. Jeongnam, who plays Mr. Bang Jeong-hwan, lives happily with his poor but single mother, Mrs. Park. The Japanese detective is played by Tae-hwan, the son of a wealthy family, and the wife of Mr. Bang Jeong-hwan is played by Young-hee, the daughter of a working couple, Jeong-suk and Hyung-tae. Tae-hwan's mother, Mrs. Yoo, is dissatisfied with Tae-hwan's role as a Japanese detective, and tries to get him to play Mr. Bang Jeong-hwan by any means necessary.