In Akabane, Tokyo, an old person, who lived alone, is found dead. The elderly person was strangled to death. Detectives from the Akabane Police Station investigate the case. According to the victim's neighbors, a woman sometimes came in and out of the victim's home. That woman is Miki Yamamoto. She does housework for her customers. The detectives from Akabane Police Station visit Miki's house. At that time, other detectives from Saitama Prefecture also arrive at Miki's house. Multiple suspicious death cases have taken place at her prior clients' homes. The media begin covering the story as a serial killer case. Who is Miki Yamamoto? What is the truth behind the cases?