Special Investigation Nine Season 1

Asawa Naoki chases a robber who escapes after robbing a jewelry store with a handgun. He suddenly runs into Shindo Ryo who begins chasing the robber with him. Naoki manages to grab the robber without any harm to the general public. The next day, while talking to his wife, Rinko, he receives a call. He heads to the police superintendent's office and is informed by Kandagawa, the police chief, that he will be forming a special investigation team.

The body of a woman in a wedding dress was found. When Naoki and the others arrive, they are informed that it may have been a suicide by pills. The identity of the body is Saito Maki, the missing concierge of a hotel. She was supposed to be married to Takemura Shigeaki, the front desk clerk of the same hotel. According to Takemura, Maki was staying alone ahead of their ceremony. Naoki and his colleagues check the security cameras but find nothing. The mystery deepens as they discover that Maki was suspicious that Takemura may have been cheating, offering a motive for the apparent suicide.

The stabbed body of Morita Akiko, a popular architect, is found. She was participating in a design competition but her design model has been destroyed by someone. The murderer may be Oya Genji, another architect also participating in the competition. After discovering cause of death, they further believe he may have been behind it. However, they soon gets new facts in the case that may point to someone else...

When freelance writer, Miyoshi Kanako, is redecorating his home, a body is found under the floor by contractor Murata Hajime. According to Inori of the forensics department, the body is male and has been dead for over 5 years. Kanako's father is former deputy captain Taizo, now suffering from dementia and of no help due to his loss of memory. Surprisingly, Taizo seemingly regains his memory and confesses that it was him...

A corpse of a puppeteer, Mitsuhashi Ryoko, is discovered by an elementary school student named Shibata Keita. Ryoko was famous for disliking children and was thus tied to Sakai Nanako, a school club instructor often visiting Ryoko's home due to complaints from parents. The team discovers shocking facts regarding the apparently accidental death of Ryoko's husband. A shocking truth emerges...

The stabbed body of talent movie producer, Kondo Rumi, was discovered. She's seemingly been struck on her right cheek and is holding an unfamiliar red flower. Certain facts emerge regarding the movie she was working on and the team pursue questioning of several people involved in the movie.

The body of Nishida Masayoshi, the president of a real estate company, is found by the steps of a shrine. Nakajima Tatsuya, an employee, is found unconscious on top of the body. The strangest part is the 10,000 yen bills scattered around them. It's revealed that Nishida was beaten to death. A third man is suspected as being involved.

The body of Yasuko, the wife of company president Mizukami Yojiro, is found their home pool. However, a v-shaped wound is found on her forehead and the home seems have been robbed. The suspects are numerous. Yasuko was disliked for trying to ensure her son will be her husband's successor while also harassing their maid, Nana. A strange paper with an infinity mark is found in Yasuko's room.

A 75 year old woman is found beaten and murdered in an Itabashi Ward park. Naoki notices that the body has swollen unnatural. In the victim's mouth, the find a fake police badge. Is the killer taunting the police? Additionally, in this same jurisdiction, there were two other murder cases where fake badges were found. Naoki reaches a shocking truth...

Takamori Tetsuya, the Minister of Justice, has reportedly been killed. Naoki rushes to the scene only to find out that the murder victim is actually Takamori's wife Shizue, confusing everyone. Adachi Yoshio discovers the apparentl murder weapon. They conclude that someone with a grudge against Takamori killed Shizue by mistake. However, the disguise of the criminal was discovered and it's believed that Shizue is actually the target. Meanwhile, the truth of Munakata's past comes to light.