Shinichi returns to the crime scene to try to keep the feeling of mourning for Kana. He is followed by a human private investigator hired by Ryoko Tamiya and Migi is caught on camera.
The private detective, Kuramori, discovers Shinichi's secret and flees from him. Concerned about Kuramori's intentions, Shinichi seeks help from Mamoru in order to track him down.
Although he still has his doubts, Kuramori reluctantly decides to help Shinichi hunt down Reiko and her group of Parasytes. But when a strange man appears, Shinichi soon goes from the hunter to the hunted.
A powerful Parasyte unlike any Shinichi has ever seen before attacks, and soon Shinichi and Migi are running for their lives. Meanwhile, Kuramori's search for the truth puts his family in harm's way.
After Reiko's judgment is called into question, three members of her own group seek to eliminate her. With Reiko otherwise occupied, Kuramori takes advantage to seek revenge for his family.
With her feelings regarding humanity and the purpose of Parasytes now in question, Reiko encounters Shinichi and Migi one final time. When police arrive on the scene, Shinichi soon finds himself at the center of their attention.
Investigators continue to hold Shinichi, certain that there is something he is hiding. In an effort to uncover his secrets, they soon bring him face-to-face with the serial killer, Uragami, who has a unique ability.
The police commence their operation to take out Hirokawa and the remaining Parasytes. However, plans go awry when the Parasytes attempt to fight back. Things take an even more gruesome turn when Gotou appears on the scene.
In the chaos of the raid, Gotou escapes and vows to return to kill Shinichi. Plagued by fear and with nowhere left to run, Shinichi turns to Satomi for comfort.