Kazuki works as a rookie host at a host club. One of his regular customers is Mai, but she disappears. Mai has a tab of 6 million yen with the host club. The bar owner orders Kazuki to find Mai within a week or Kazuki will have to pay back her debt. Kazuki turns to problem-solving office Kurogarasu. There, Kuroto, Yuya and Hina are hired by Kazuki to find Mai and he offers them 3 million yen.
One day, Chizuru (Nana Asakawa) and Mioto (Aino Kuribayashi) enters problem-solving office Kurogarasu. The two girls look naive, but Chizuru is a leader of a enjo kosai group. Their group makes money by having young girls date older men for money. Thugs are threatening Chizuru for money. Chizuru pays 2.5 million yen to the problem-solving office Kurogarasu for their help. Kuroto (Tsubasa Sakiyama), Yuya (Keisuke Ueda) and Hina (Moga Mogami) take the case and begin to investigate the thugs, but they find something unexpected.
Mashiba Riku , who has a past of betraying his friends and going on the run, he comes to Black Crow leader Kanzaki Kuroto and his right-hand man Masato Yuya. Riku says he is setting up a problem resolution agency called White Knight.
Prequel in the "Black Crow" series about an agency that resolves underworld troubles, set in Shinjuku's red-light Kabukicho district. The story focuses on the protagonist's hidden past. Rookie police officer Kanzaki gets posted to an area that has descended into anarchy. He gets a hand from fellow police officer Hyodo and they strive to do their jobs. Then, a criminal group's hideout gets burglarized and the incident escalates into murder.
