Dr. William Janus made his first and so far only appearance in Season Fifteen episode "City Sushi". Dr. Janus is the host of Tuong Lu Kim, proprietor of the City Wok Chinese restaurant.


Dr. William Janus becomes Butters Stotch's therapist after he inadvertently starts an Asian Turf War between Junichi Takiyama owner of City Sushi and Tuong Lu Kim's City Wok. The doctor sends Butters on a mission to investigate "Billy", one of Janus' other alters, and discovers Tuong Lu Kim is and always has been yet another alter of the therapist.