Kyōka Izumi/Synopsis

Armed Detective Agency vs. Port Mafia Arc
Kyōka first appears in the city, seemingly waiting for someone. Soon, she spots her target, and uses her ability to apprehend Dazai, leaving him in Port Mafia's capture.

Afterward, when Atsushi Nakajima was out shopping with Akiko Yosano, they passed by each other without thought. but Atsushi notices her focus on him for a brief moment. Later on, on the train attacked by Motojirou Kajii, she encounters Atsushi once more, and Akutagawa orders her to protect the bomb on the train with her life, thus attacks Atsushi. After injuring Atsushi severely, she introduced herself as an orphan, listing her likes and dislikes, and confessing to her 35 murders within the span of six months. Their battle continues, but Atsushi soon deflects her. Kyōka shocks him, pointing out the last three victims were a family of three and expresses little emotion. However, after Atsushi urges her to express herself, she wavers. She gives Atsushi the detonator to deactivate the bomb, but it is remotely force-activated after Akutagawa notices the button was pushed. Finally breaking from Port Mafia's influence, she attempts to sacrifice herself by jumping off the train with the bomb. Atsushi saves her and rips the bomb off of her, and the two fall into the river.

She wakes up in the Agency's infirmary. Atsushi and Kunikida persuade her to talk of the mafia's plans with tofu. Atsushi later shows her much of the city she never saw whilst in the mafia, showing her a new side of life. However, at the end of the tour, Kyōka intends to turn herself in to the police, aware of her unforgivable crimes, and that it is either imprisonment or mafia's execution awaiting her future.

Atsushi, however, is attacked by Akutagawa, who forces Kyōka to come with him. The three all depart on a cargo ship intended to take Atsushi to the people responsible for his bounty. Nonetheless, Kyōka intends to defy Akutagawa anyway, and sets a bomb off to sink the ship with her and Akutagawa with it. Akutagawa overpowers Kyōka and nearly kills her, but Atsushi saves her. After Akutagawa and Atsushi's showdown, Kyōka saves a badly weakened Atsushi from the sinking ship, landing in a rescue boat piloted by Kunikida.

Returning to the Agency, majority of the detectives celebrate Atsushi and Kyōka's success against Akutagawa, with Yosano and Naomi dressing her up in an outfit. However, when explaining her intentions of joining the Agency, Kunikida points out it won't be easy to deal with her and the crimes she committed, as many forms of authority will want her in their custody. She begs Yukichi Fukuzawa to let her join, saying she wants to prove Akutagawa wrong, that she isn't just a killing machine. After an intense staredown, Fukuzawa hires her.

Dazai arranges for Kyōka to room with Atsushi, both out of convenience and in favour of her safety against any mafia assassins who may attempt to kill her for abandoning them. Long after Atsushi and Tanizaki's run-in with Lucy Maud Montgomery, Kyōka runs up and hugs Atsushi in relief. Her relief is short-lived. Wearing civilian attire, Port Mafia's boss approaches an unsuspecting Atsushi, praising his efforts against Lucy, and walks away. His sudden appearance terrifies Kyōka to a trembling, speechless state that brings her down to her knees.