Affiliation: None. Ranked 100th in the Killer Ranking. Weapons: Hand axe and dagger. Capable of sensing killing intent and possesses a massive amount of it himself. He owns the Silver Hair badge, Crown badge, CT.100 badge, and Hair Clipper badge, but keeps the Silver Hair and Crown badges hidden without tagging them. He is the disciple of the deceased Silver Hair and usually travels with Dr. Stitch (except during missions). He wears black and white striped clothes. He became significantly stronger after training under Gurimu and JUST.KO (strong enough to rival Rhabdophis). He has even infiltrated the King & Kill Chairman's office. He calls almost everyone by the wrong name (except Dr. Stitch, Gurimu, and Ipan/Sapan). Examples: Rhabdophis -> Bloody Mess, Knight -> Nightclub, Tteokbal -> Rice Cake Shop Ahjussi. Before fighting a killer, he always says, "I will kill you, by any means necessary." This is the only time he uses polite speech.

A long-time friend of Silver Hair who treats Silver Hair's disciple, Just Go. He previously treated Silver Hair when he was injured during training and advised Just Go to follow in Silver Hair's footsteps if he wanted to become a ranked killer. He considers Just Go a madman. As a specialized doctor for killers, he is unranked. He is a man with white hair and light purple tinted sunglasses.

Twin killers. When separate, their killing intent is red, but when together, it turns orange. Ipan: Calls Mammoth 'Baldy' and is ranked 70th. Sapan: Calls Mammoth 'Fatty' and is ranked 71st. Both use kunai as secondary weapons. Ipan's true weapon: Kusarigama (chain-sickle). Sapan's true weapon: Dual Katanas. When together, they are ranked 22nd. Both are aware that Phone 5 is a spy.

The developer of the Killer App and a member of King & Kill. He has a stutter. He is unranked and possesses no killing intent. He wears glasses and a headset around his neck. He knows Phone 5 is a spy but is too intimidated to say anything.

Ranked 36th, but possesses enough skill to easily take down an 18th-ranked killer. His weapon is a katana. Member of King & Kill. Has white hair and wears white clothes with black pants. He is the only one who listens to Knight's ramblings. Signature move: 'Ildo Yangdan' (Cleaving in two with a single strike).

Male, member of King & Kill, ranked 5th. His weapon is a katana. He only uses polite speech with King. He has gray hair. He is actually a spy from the Viper Club. Within the Viper Club, he is unranked, goes by the name 'Neungsa', and is the leader. Even though he is Neungsa, he continues to operate under the name Phone 5.

Male, ranked 13th. Given that he talks to everyone about Sweet Potato Aliens and Broccoli Chimpanzees, his mental age is... questionable. His main weapon is a spiked bat. Member of King & Kill. Wears black sunglasses and black clothes. He is grateful to Phone 6 for listening to his stories.

Male, ranked 20th. Due to a misunderstanding, he tries to recruit Just Go. Member of the Viper Club. Wears purple clothes, has black hair, and orange-tinted sunglasses. He has a vertical stitched scar over one eye.

Male, ranked 27th. His weapon is a machete. Member of the Viper Club. Has medium-length orange-red hair and wears red-tinted sunglasses with black clothes featuring orange patterns. He has horizontal stitched scars on both sides of his mouth.

An elderly man. Though he has dropped out of the rankings due to age, he remains powerful with a massive amount of purple killing intent. He was once Silver Hair's greatest rival. He taught Just Go techniques like the 'Groin Kick' and 'Groin Squeeze'. He has gray hair covering his face. He is aware that Phone 5 is a spy.