Tuong Lu Kim is an alter ego of Dr. William Janus and the owner of the local City Wok restaurant and City Airlines. His stereotypical Chinese accent is used for humor, causing him to mispronounce words such as 'city' as 'shitty'. He debuted in "Jared Has Aides" and has remained a recurring character since, though his true identity was not revealed until "City Sushi".
In "Jared Has Aides", the boys prank-call him, then approach him about Butters becoming City Wok's "Jared". After the real Jared announces he has "aides", Lu Kim decides he doesn't want his own "Jared" and the kids become angry with him. At the end of the episode, after everyone discovers the difference, he offers the boys $15 (pronounced "fifteen dorra") and the boys refuse.
Later in "Child Abduction is Not Funny", he is asked to build a wall around the town to protect the city from kidnappers (and Mongolians raiding the town for no apparent reason other than to be an inconvenience to Lu Kim). Lu Kim expresses great frustration but ultimately fails his goal, becoming even angrier when Mayor McDaniels requests he "tear down this wall".
In "It's Christmas in Canada", the boys contact him via "City Airlines" in hopes of going to Canada to rescue Kyle's brother and speak with the Prime Minister of Canada. They haggle him down to $62 (although Lu Kim thinks that he haggled them instead) to take the four of them to Canada. During the flight, his Cessna runs out of gas and crashes, but not before he jumps from the plane with the only parachute. It is unknown how he managed to get out of Canada and back to South Park, though presumably, he followed the only road back.
He reappears in "Wing" briefly where he introduced the boys to his wife, Wing. Later, the Chinese Mafia arrives at City Wok and forces him (by dumping trays of his food over the counter) to tell where Wing is. Lu Kim then appears at the end of the wedding.
Tuong Lu Kim can also be seen in the crowd at the end of the episode "The Coon".
He reappears in "T.M.I." where he, along with a group of Anger Management people who are mad about the sizes of their penises. Just a few episodes later in "City Sushi" however, he reappears angry that City Wok now has competition with City Sushi right next door. He is shown to have a deep hatred for Japanese people, consistently trying to kill the City Sushi owner and humiliate him, proposing peace treaties including an Asian Diversity assembly at the school and then an Asian Diversity festival, using a peace tower at the latter plot in hopes of killing the owner and framing it as a suicide (which he claims is what Japanese people like doing most).
Meanwhile, Butters Stotch is seeing a psychologist named Dr. Janus for Dissociative Identity Disorder (referred to in the episode as Multiple Personality Disorder) though he quickly discovers Janus suffers from the disorder himself. Dr. Janus soon begins to haunt Butters because of this through several personalities. He even frames Butters for bedwetting and bank robbery. Janus' young boy personality ("Billy") asks Butters to help him stop an evil personality and leads him to his mansion where Butters discovers Janus has photographs of Takiyama labeled 'Kill'. It is then revealed Dr. Janus is Tuong Lu Kim, and Lu Kim is only a personality and the strongest personality of Janus. At the Tower of Peace, he reveals his plan to Takiyama and tries to kill him but the police arrive and reveal to him that he's not Chinese but white. Lu Kim and Takiyama appear clueless at first but when Lu Kim begins changing between personalities, Takiyama is ashamed that he believed that a white man was Chinese and kills himself by jumping off the tower.
After Lu Kim is arrested, Sergeant Yates resolves they should let Janus keep believing he is a Chinese man, not telling him about his disorder, and send him back to his restaurant after he gets processed, rather than keep him arrested, explaining City Wok is the only Asian restaurant after the incident and it will get more money anyway and he would be harmless as such. In his cell, he is continuing to plot to kill any more Japanese people who try to ruin his restaurant's business, thinking they are probably watching him but Lu Kim decides he will try to act harmless.
As of "Cock Magic", it has been shown that Lu Kim has been released from prison and is back to normal, although the town seems to be aware of his true nature, as it is referenced by PC Principal in "Stunning and Brave" to little surprise or reaction.
Tuong Lu Kim wears a white collared shirt with a red bow tie, an orange City Wok vest, and blue pants. He also has a gold watch in his right hand. His hair is black and has a comb-over to hide his balding. He has one tooth sticking out from his mouth when it is closed and he has lines defining his cheeks and chin. His eyes are almost always closed due to the stereotype seen in the series that Asians always have small eyes, but are occasionally seen open.
From Season Fifteen's "City Sushi" on, his vest is straightened out a bit and he now wears dark gray pants. His hairline is slightly modified and his cheekbones and chin are now an off-flesh color instead of black, like many other characters in later seasons; he occasionally reverts to his previous design.
Although its canonicity is disputed, Lu Kim plays a major role in the video game South Park Let's Go Tower Defense Play! as an assistant in the "Great Wall" level where he is once again asked to build a wall around the town to keep out enemies. He pours hot sauce over parts of the level at random times that can damage enemies heavily. He is not a playable character.
City Wok, City Sushi, and the Tower of Peace appear prominently as locations in this game. Lu Kim's store is taken over by Mongolians who force him to sell Mongolian beef and live in the Tower of Peace constructed during "City Sushi". He dispenses 'potions' and power-ups at his store and adds your character as a friend on Facebook if you complete a quest for him against the Mongolians. He can also be summoned into battle to do his battle dance to instantly win any encounter apart from boss battles, but only once per day.
- His name makes his ethnicity vague: Tuong (correctly Tường) is a Vietnamese given name, Lu (卢 or 陆) is a Chinese surname, and Kim 김 is a Korean surname. However, it's worth noting that Lư and Kim are both (rare) Vietnamese names as well.
- Lu Kim's real name Dr. Janus is a reference to the Roman God Janus which is normally depicted with two or more faces; a clear reference to Kim's multiple personality disorder.
- Lu Kim's real first name is presumed to be William as his child's personality goes by the name "Billy".
- Lu Kim was possibly molested as a child due to Janus' claim that the personality of Billy had been molested.
- Lu Kim suffers from male pattern baldness and usually has a combover, though while Janus wears a headpiece to cover the bald spot.
- Lu Kim and Janus share very few similarities animation-wise besides actual facial shape - his nose, eyebrow shape, mouth, and facial wrinkles all change during the same slight of the hand he uses to create the combover in his hair.
- In "Conjoined Fetus Lady", one of the announcers at the Dodgeball Game in China bears a strong resemblance to Lu Kim, though his eyes are open and a small mustache. Considering the revelation of Lu Kim as one of Janus' identities, and the announcer being seen in China, it seems unlikely the two characters are one and the same.
- In "Butters' Very Own Episode", the man who sold Butters a ticket to the White Swallow sounded very much like him but his face wasn't seen through the glass.
- Lu Kim's real mind, Dr. Janus, is aware of his Billy personality, as he tells Butters to not mind him. He may however have thought that Billy was another person in the room or another patient. Later though, it appears that even Janus himself does not know who his multiple personalities are.
- Lu Kim's voice is very similar to that of North Korean leader Kim Jong-il in Team America: World Police, also voiced by Trey Parker.
- As Dr. Janus is an actual professional psychologist, it is unknown how he was able to have this job and be able to run City Wok as well. Although with more jobs, he must be very rich, which would explain why he lives in a mansion.
- "Jared Has Aides" - Debut appearance. The boys prank-call him and then approach him about Butters becoming his own "Jared".
- "Child Abduction is Not Funny" - Instructed by Mayor McDaniels to build a wall to keep children from being abducted.
- "Krazy Kripples" - Mistakes Jimmy and Timmy as gang members when they enter City Wok.
- "I'm a Little Bit Country" - Seen singing with numerous other characters at the end of the episode.
- "It's Christmas in Canada" - Flies the boys to Canada.
- "Douche and Turd" - Seen in the crowd.
- "The Coon" - Seen in the crowd at the end of the episode.
- "T.M.I." - Angry about the size of his penis and participates in a group therapy session.
- "City Sushi" - Revealed to be an alter ego of William Janus.
- "Cock Magic"
- "Stunning and Brave" - Seen at the meeting at South Park Elementary.
- "The City Part of Town"
- "You're Not Yelping" - Brings food to Eric Cartman.
- "PC Principal Final Justice" - Seen in the crowd of people standing in front of Whole Foods Market.
- "Let Them Eat Goo" - Attempts to do a deal with the Goo Man.
- "The Pandemic Special" - Seen at Randy's presentation and later at the hospital with a mustache.
- "South ParQ Vaccination Special" - Seen outside Walgreens waiting in line for the COVID-19 vaccine. He is also seen at the end, celebrating the end of the pandemic.
- "Pajama Day" - Seen wearing his pajamas while dancing on Pajama Day.
- "City People" - Notices the danger from the City People buying the town's homes.
- ""South Park" Jared Has Aides (TV episode 2002)". IMDb.com.