In the Narcotics Investigation Division, a series of investigator disappearances have occurred, causing a severe personnel shortage. Amid the crisis, elite agent Mitsuki Nagisa is newly assigned. Driven by a strong sense of justice and a burning desire for revenge, she throws herself into the investigation—but soon takes reckless action. Gathering intel on the Kuroshikai's Moriyama Group, she heads alone to the AJITO building, only to walk straight into a deadly trap. Captured and forcibly administered the very illegal substance she was investigating, Mitsuki’s fate takes a drastic turn—what lies ahead for this elite investigator caught in a dangerous investigation where justice and revenge collide?