Octo: Emotional Investigator Shinno Akari

Detective Shinno Akari of Higashi-Kanagawa Police Station has the ability to see the emotions of people she makes eye contact with as colors, triggered by a shocking incident 15 years ago that killed her parents. One day, an 18-year-old girl, Sakiko, jumps off the emergency stairs of a hotel with her boyfriend, Shunsuke.

Kokoro no Akari and Kazehaya Ryo are questioning novelist Suzumoto Chizuru. Chizuru's husband, Takuto, and Mikoto, a woman living on the upper floor of the same apartment building, are found dead. Mikoto was stabbed multiple times with a knife and died. Takuto was found dead with a knife still stuck in his stomach.

A patient, Hanae, dies in a hospital, and nurse Asami is arrested on suspicion of murder. During questioning by Akari and Kazehaya, Asami confesses, "I killed her," hinting at a murder for pleasure. Indeed, what Akari saw from Asami was yellow, which represents joy.

Akari attends the funeral of Akiko, the hospital director who looked after her 15 years ago. During the funeral, Akiko's secretary, Shiota, takes Akiko's relatives hostage and barricades herself inside, and Akari gets caught up in the incident. Akari sees a light blue sparkle in Shiota's eyes, which indicates "surprise." Shiota is afraid that Akiko will be killed by someone in her family...

Akari and Kazehaya are investigating the popular flower artist Maruyama.Evidence is found that suggests Maruyama killed someone and buried the body, but Maruyama says that he has lost part of his memory due to the shock of a traffic accident and has no idea what he did. Akari sees a light green color in his eyes, which represents "anxiety."

Akari and Kazehaya are investigating Michiko, the suspect in the murder of Kawase, a building cleaner. Michiko confesses to killing Kawase, but refuses to reveal any motive. Akari cannot read any emotion in Michiko's eyes. She has had such painful experiences that she cannot survive without losing her emotions...

Akari and Kazehaya are investigating Yamato, a university student who has been arrested on suspicion of assault. A settlement is soon reached with the victim and the investigation ends. Yamato is not satisfied, even though he will be released. Akari sees the red in Yamato's eyes, which represents anger. Yamato's father, the head of the family, is the one who is investigating the murder that occurred 15 years ago...

Akari and Kazehaya investigate an incident that occurred 15 years ago. At the time, Akari's father Yosuke was a detective at Higashi-Kanagawa Police Station, investigating a series of rapes of women. Watanuki was arrested as a suspect, but was released due to insufficient evidence. Later, another murder of a woman occurs using the same method.Heian...

Akari comes face to face with Onodera, who has turned himself in. Worried that confronting Onodera will cause Akari distress, Kazehaya conducts the interrogation alone. However, Onodera insists that he will only talk to Akari. Akari confronts Onodera. As Akari continues to interrogate Onodera, her sketchbook is filled with black. However...