Policewoman Yukari Morikawa investigates a cursed M1911A1 handgun, dubbed "The Evil.305 Handgun," which unleashes violence after falling into student Yuu Asakura’s possession. Her pursuit faces internal police obstacles, with certain colleagues hindering her progress. Despite departmental resistance, Morikawa remains dedicated to solving the case, valuing the investigation above career advancement. She will circumvent official orders if necessary to achieve her goals. Her duty sidearm is a Heckler & Koch USP pistol chambered in 9x19mm, and she maintains a consistent presence throughout the series.