Kimongai Karma is the direct sequel to the manga Kimongai, also known as Kimongai -City of Demons-, created by Kouichi Nagata. The story follows Masato Kawashima, a high school boy born in a crime-ridden district shunned as a demon gate. After his mother is murdered and he is beaten nearly to death by thugs, a demon named Gouki appears before Masato and offers him a pact. Masato sells his soul to Gouki and gains immense demonic power. With this power, he encounters various incidents, but his quest for revenge intensifies when the killer who murdered his mother also attacks his father, leaving him in a coma. Masato is then forced into a deadly battle royale orchestrated by a mysterious onmyoji, who implants bombs in the heads of demon-possessed fighters and forces them to participate in a game called Karma. The narrative follows Masato as he fights other demon hosts, confronts his mother's killer, and uncovers the truth behind the demons and the city's cursed nature. Key characters include Masato, his demon partner Gouki, his classmate and fellow demon host Wakutani, and a rogue taxi driver with his own connection to the demonic world. The setting is a gritty, contemporary Japanese urban environment plagued by violent crime and supernatural corruption. Notable arcs include Masato's initial transformation and quest for revenge, the forced participation in the Karma death game, and confrontations with various rogue demon hosts such as a sadistic teacher, a serial killer in a Halloween rabbit costume, and the boss of a special fraud group who can manipulate pain and pleasure. The series explores themes of revenge, the corrupting nature of power, and the darkness within the human heart.