Tantei no tantei

Sasaki Rena is training hard in the gym of Suma Yasuomi's Detective Agency "Suma Research." Rena is the sole detective in the agency's "Anti-Detective Department" that investigates detectives, but she is soon joined by Minemori Kotoha, a newbie brought in by Suma. Suma tells Rena that Kotoha is to be her assistant, but Rena insists she can handle the department hersel...

While Sasaki Rena is out, Abiru Yoshinori arrives at the Suma Research Company. When Suma Yasuomi and Minemori Kotoha go to meet him, he informs them that he met Rena the previous day. Furthermore, he gives them a small box tied with a ribbon and asks them to give it to Rena. Suspecting a listening device may be planted inside the box, Kotoha decides to check at the suggestion of the Detective Department's Doi Shuzo.

Yabuki Yoko, the doctor who performed the DNA analysis of Sasaki Sakura five years ago, tells Sasaki Rena that suspect Okao Shinya, who was thought to have died with Sakura, is still alive. Furthermore, he may be involved in the kidnapping of a young girl that occurred a few days prior, and the police are currently working with a detective to capture him. Rena asks about the detective, but Yabuki says she doesn't know anything about him.

Following Abiru's instructions, they head towards the suspect's location. Suddenly, the sound of footsteps cuts through the tense air. As the detectives gaze into the dimly lit room, they find Sasaki Rena covered in wounds and dragging a metal pipe. When Rena comes to Abiru, she shifts her gaze to Yabuki Yoko standing at his side.

Sasaki Rena decides to visit a now conscious Hiike in the hospital. The investigative report on Isawa Kyoko, a woman Hiike once stalked and murdered, closely resembles Sasaki Sakura's report. Based on the fact that the reports were created one after another, Rena suspects they may have been written by the Death God and believes she can get the truth out of Hiiike.

Sasaki Rena runs into Kubozuka Yuma outside the apartment of Masuse Atsushi, the husband of Ashiharu Haruka, a woman who fled from a domestic violence shelter. Kubozuka reveals the police suspect Rena killed Hiike in the hospital the other day and warns her to keep a low profile. Once he leaves, Rena tells Minemori Kotoha to return to Suma Research and look up which bank Masuse is using.

Sasaki Rena is captured by the loosely organized crime group "Nohozu." When she comes to, she finds herself in a gloomy bar. Around her, Masuse Atsushi and the other abusive husbands and boyfriends huddle together. When Yodono Eito arrives and sees Rena, he demands to know who she is. Instead of answering his question, Rena accuses him of hiring a detective to find the facility harboring the domestic violence victims and says she has business with him.

After the tragedy of the attempted rescue of the domestic violence victims, the gravely injured Kubozuka Yuma is taken to the hospital. Sasaki Rena gets in Minemori Kotoha's car and instructs her to drive to the airfield. To protect Kubozuka from the disgrace of being charged with causing bodily harm, she wants to erase the images taken from the air by the police.

Sasaki Rena and Minemori Kotoha visit a woman named Takahashi Rika. Rika's brother married Sawayanagi Nana and died eight days later under suspicious circumstances. The doubtful Rika hired the Abiru Detective Agency to investigate the matter. Rika shows Rena the investigative report written on Sawayagani. In it she finds a copy of her high school yearbook, which contains a photo of Sawayanagi.

The man Sasaki Rena incapacitates with her stun gun is detective Kamoi Shuichi. When Rena asks why she's being investigated by a legitimate detective agency, Kamoi explains that he's not the only one after her. Detectives Kodama Shoji and Kurokawa Yusuke appear before Rena as well. The three claim to belong to another agency's Anti-Detective Department. From the shadows, another figure secretly observes their interaction.

Sasaki Rena asks Ichimura Rin, the woman standing before her, if she is the Death God. Ignoring her question, Rin asks if Rena is frustrated that she failed to see through her disguise. Minemori Kotoha interjects, but in a totally unprecedented manner, Rin yells at her to shut up. Rin begins describing the countless crimes she has committed until this point. As Rena calmly listens, Rin demands to know why the normally quick to act Rena hasn't attacked her yet.