Detective Masaharu Tamura serves with the Kyobashi Police Precinct's Criminal Affairs Division. A veteran detective, he employs an athletic, headlong approach to police work, frequently rushing into situations. Tamura possesses a fervent passion for punishing the wicked and maintains an unwavering focus on justice. Initially unaware of his subordinate Yasuda Ippei's affluent background and connections, Tamura recognizes Ippei chiefly as an individual overflowing with a sense of justice. He approves of Ippei's dedication and assumes a mentorship role. This relationship sees Tamura guiding his less experienced colleague, sometimes harshly and sometimes kindly, as a senior officer. He directly partners with Ippei on investigations, including examining a deceased female university student found within their jurisdiction and probing the significance of a '4' branded on her neck.