It's difficult to determine the exact facts on Tuong Lu Kim's original identity - what is known is he is a white man who has lived in South Park, Colorado for at least seven years and works as a psychiatrist - oh, and he was molested by his uncle. His alternate personas include a small child version of himself known as "Billy", a violent evil psychopath, a kindly old man, a pizza delivery guy, and City Wok proprietor Tuong Lu Kim. After Butters Stotch reported his condition, he was processed by Harrison Yates and the Park County Police and released as Lu Kim.
- "Oh, so you're on to me, huh, you little shit?" (City Sushi)
- City Sushi (s15e06)
- He identifies his younger self as Billy, both in and out of the persona, so his first name is almost certainly William.