Ishikawa has a showdown with Ando Chikao (Omori Nao) who kidnapped and murdered his own 8-year-old son on the rooftop of an apartment building. At that time, Ando provoked Ishikawa by declaring that Ishikawa would always lose to him because the justice he practices is “halfbaked”. Then taunted him by welcoming him to “this world”. Ishikawa swayed between right and wrong and was forced to make the ultimate decision for the sake of his own justice and revenge for the dead. While shock waves run through the people who know Ishikawa well, Kudaka Takeshi (Kunimura Jun), the director of inspection, begins interrogating him at the headquarters. Although Kudaka has a genial demeanour, he is very observant and gets a strange feeling from Ishikawa. In the middle of the interrogation, Ishikawa encounters a beautiful woman Sudo Mami (Nakamura Yurika) on the streets. He hears her pleas to catch the person who killed her and takes unexpected action. What is his final decision?

Set before the events of BORDER, we follow forensic scientist Higa Mika as she struggles to step out of Professor Asakawa Toru's shadow and become an independent scientist.

For some reason, it seems that she's stuck being his assistant and can't progress any further, when a female junior high school student gets strangled in the jurisdiction of the Nishihara Police Station.