Synopsis: Sachiiro no One Room Gaiden - Seikai no Meitantei

This is a derivative story centered on Hijiri Matsubase, delving into his life prior to meeting xxx by three years. Matsubase had resigned from the police force to chase after his ambition of establishing his own detective agency. Nevertheless, his new venture experienced a low level of success, resulting in a colossal amount of debt after he was duped by a con artist. Along came Aketoyo, the son of a prosperous billionaire, and the same deceiver who scammed Matsubase earlier. Aketoyo, who is sly and deceitful, lures Matsubase into a risky bargain by offering him ¥10,000,000 for each case he works on if he entertains him. Therefore, Matsubase cannot resist the irresistible temptation of the offer and agrees to make a deal with the dangerous devil.