Kouki Atsumi

Kouki Atsumi is the homeroom teacher of Class 2-3 in Kiyou High. He serves as the primary antagonist of Volume 1.

Appearance
Atsumi is a smart-looking man with black hair that is slicked-back. He has a mole on his forehead and wears spectacles. He wears a black overcoat, a white dress shirt and a black necktie with white stripes on it.

Personality
Atsumi is a friendly and approachable man who is willing to sit down to listen to the problems of others and give them advice. This causes him to be popular among the students of Kiyou High. However, his personality changes drastically when his Bloodlust activates. He becomes a cruel and sadistic man who has no qualms about committing murder. He also shows a lustful side of him.

Plot
Atsumi is Taku Kamishiro's homeroom teacher and teaches classic literature. He first appears when he sees Kamishiro picking up trash on the hallway. He gives the young man a rub on the head while advising him to remember to talk with others about his problems instead of dealing with them himself. Kamishiro thanks him in his heart and looks on as Atsumi is given birthday presents from students. When he is done, Atsumi is approached by another student, Yamada.

Behind the scenes, Atsumi and Yamada conspired to kidnap Mika Hanazono and murder her, for the two had been infected with Bloodlust and were in love with her. After Hanazono was driven out of Kamishiro's home, Atsumi drives his car next to her, with Yamada in the back, pretending to ask her for directions. Letting her guard down, Hanazono was rendered unconscious when Yamada held a handkerchief with chloroform in it to her face. Atsumi then drives Yamada and the unconscious Hanazono to a warehouse where they planned to murder her. Unbeknownst to the two, Kamishiro was hot on their heels and pursued them to rescue Hanazono. He got run over by a car, and Atsumi assumed it was just an animal that was run over. Atsumi asks if Yamada got him a raincoat, as things will get bloody later on. At the warehouse, Atsumi argues with Yamada on how they should murder Hanazono. He preferred to stab her vitals with a knife while Yamada wanted to do it slowly and torturously. They were interrupted by Atsumi's phone ringing. Atsumi picked up the phone when he saw it was Kamishiro calling. Kamishiro recited what Atsumi once taught him; one must first overcome the darkness in their heart in order to subdue evil. While the conversation is going on, Kamishiro enters the warehouse, expressing disbelief that the teacher he owed so much was a criminal. Kamishiro tries talking Atsumi and Yamada out of killing Hanazono and dashes at her to murder her once he sees her. Atsumi restrains Kamishiro, recognizing that he has Bloodlust as well and welcomes him with open arms. He reveals that he fell for Hanazono, who had a 'nice scent' when the two crossed paths once. Atsumi proceeds to put his head under Hanazono's shirt, driving his face against her breasts while Yamada laughs at him. Atsumi takes his responsibility as a teacher to educate Yamada and Kamishiro on how to butcher someone. He prepares to kill Hanazono.

Atsumi is then betrayed and stabbed numerous times by Yamada, who wants killing Hanazono all for himself. He is badly wounded, but has enough strength to bludgeon Yamada repeatedly with a metal pipe in revenge after the latter was defeated by Kamishiro. He turns to ask Kamishiro if he intends to betray him and wishes that he would not have to kill a good, sensible boy like him. Kamishiro, however, attacks him, and Atsumi knocks him unconscious with a blow to the side of the head. During the time Kamishiro was unconscious, Atsumi heavily mutilated Yamada's body and left it an unrecognizable pile of flesh with the skeleton exposed. He rigged the warehouse with explosives to leave no evidence behind and staggered away.

Badly wounded and his face slightly disfigured, Atsumi curses Kamishiro and encounters a man. He explains that he and his drunk friend got into a fight which is why he is injured and tells the man to pay him no attention. The man quickly touches Atsumi without him noticing. Atsumi suddenly bleeds from inside, with blood gushing out of his eyes, nose, mouth and scalp, and dies shortly after. The man tells Atsumi's corpse that he has played his role and that his time was up.