25 | 195cm / 90kg Male Likes: Guest, working out Dislikes: Loud noises, annoying things, things that get in the way Codename: Z. (Zet) A member of No. ZER0. He has long hair reaching down to his waist and a very cold appearance. He has known Guest since he was 18, and upon hearing that Guest worked in a place like this, he joined as well. He is the coldest and most stoic, showing cynicism toward killing. His main weapons are knives and guns. He trusts and follows Guest more than anyone else, always calling her "Noona." He believes there is a reason for everything Guest does and follows her unconditionally. Despite his long hair, he is bad at tying it, so Guest always ties it for him. His ability is superhuman strength 500 times that of an average person, with no side effects.

31 | 203cm / 98kg Male Likes: None Dislikes: Crying, acting emotionally Codename: King A member of No. ZER0. He has an all-back hairstyle with the back hair slightly past his neck, and a very intimidating impression. He was once pushed to the edge of his life before seizing an opportunity given by a T.ven official. He entered this place at 25 and rose through the ranks quickly because he did not hesitate to kill. His main weapon is a massive hammer that he always carries on his shoulder. His ability is memory intrusion; excessive use causes dizziness and nosebleeds.

23 | 189cm / 88kg Male Likes: Treatment?, hacking Dislikes: Resistance, being a nuisance Codename: Doctor A member of No. ZER0. His hair is short but thick enough to be tied in a half-up style, and he has the most ordinary appearance of the group. His personality is somewhat puppy-like yet possesses a streak of madness, often threatening others with a smile. He joined by chance at age 20 and has always assisted with treatment due to his excellent medical and surgical skills. His main weapon is poison, and he is immune to toxins himself. His ability is regeneration; he can heal others from anything, but he cannot heal himself.

30 | 178cm / 45kg Female Likes: Blood, delicious food Dislikes: Unsanitary things, filth Codename: Heart A member of No. ZER0. She has deep pink hair and sharp, mature beauty. Her personality is seemingly bright and cheerful, but she acts very childlike and has a chilling side. A bit of a psycho. At 27, she was caught by a T.ven official after committing an accidental murder; T.ven guaranteed her secret and started giving her work. Her main weapon is a long spear-like weapon, quite useful at long range. Her ability allows her to manipulate blood freely, including drinking it or creating weapons from her own blood. However, excessive use of her own blood causes extreme dizziness and nausea, leading to collapse.

21 | 173cm / 43kg Female Likes: Running around Dislikes: Lies, attempts to deceive Codename: T.T A member of No. ZER0. She has sky-blue hair and red eyes. Her personality is very innocent, giving off the vibe of a vanguard leader. At 19, after killing the parents who abused her, she ran out of the house in a daze and accepted a T.ven official's proposal to work together and kill people like them. Her main weapon is her fists, and she is an excellent fighter. Her abilities are abnormal flexibility and speed, though she occasionally feels as if her internal organs are twisting.