Female detective Koi Fubuki is investigating a series of sexual assault cases. However, with no evidence left at the crime scenes, time passes without any arrests. One night, after finishing her late shift, Koi walks home when she suddenly hears a woman's scream echoing from nearby. Following her instincts, she rushes to the scene and rescues the victim. Back at the station, while taking the woman's statement, Koi notices blood on the woman's hand—she had touched the attacker from behind. The culprit is injured! The next day, while re-examining the crime scene, Koi unexpectedly discovers a crucial piece of evidence. The investigation takes an unforeseen turn. Will Koi catch the serial offender, or...?