Kenji Matsushita is a reportage writer. While he was interviewing the tattoo contest, he met a woman with a tattoo of a large snake, Kinue. Kineda is the mama of the bar and the wife of the president of the earth-moving company, Mogami. She was a sympathetic woman, and Kenji was drawn to her body and spent the night together. The silk branch was found in a dismembered corpse in the bathroom of her apartment, and the carved torso of the snake disappeared. Since the bathroom was completely closed, the investigation was stopped. So Kenji consults with his lover, Nobuko's older brother, Kyosuke. Kyosuke is a genius, and he solved the mystery of the closed room without difficulty. However, the criminal cannot be identified yet.
Unfortunately the movie Detective Kyosuke Kozu's Murder Reasoning I is not yet available on HBO Max.
| Directing | Masahisa Sadanaga | Director |
| Writing | James Miki | Screenplay |
| Writing | Akimitsu Takagi | Original Story |
