Kosuke Hasumi, an ace detective at the Sakura-machi Central Police Station of the Tokyo Metropolitan Police Department, is partnered with Eiji Kikkawa, a detective who was transferred from the Organized Crime Division, commonly known as "Maruboshi. Hasumi is bewildered by the gangster-like Eiji Kikigawa in appearance and behavior, but one day, while investigating together, Hasumi learns of a serious secret from Kikigawa. Kikukawa, who wants to take credit for his return to Marutoh, presses Hasumi to "cooperate with me in scoring points in exchange for keeping the secret quiet. On the other hand, Kosuke, who wants to achieve a certain goal, accepts and says, "If you want to do that, I'll use your connections and experience."