This film is an adaptation of a short story of the same name, written by Kao Yi-feng. It tells the story of a green scarab beetle who has transformed into human form. As in the book, he is named "Vitamin." Vitamin surreptitiously enters people's apartments and observes and imitates human behavior. Through Vitamin's perspective as a bystander, the plot leads the audience to explore the unknown stories of various residents. However, Vitamin cannot understand the complex thoughts and desires of humans, and his short encounter with one person is fraught with doubt, conflict, and
 despair.