Shinichi Shitara, a detective working in the First Investigative Division of the police station, lost his wife in an accident two months ago and has been living with his daughter Kaori ever since. The relationship between Shitara, who is devoted to work, and Kaori has been strained ever since his wife died. One day, a housewife was electrocuted to death in a locked room in an apartment building under Shitara's jurisdiction. A few days later, another electrocution incident occurred in the same jurisdiction. The only thing the two incidents have in common is that the victim's child attended the same school, and that a robot called "TOYD" was left in the child's room. Could TOYD be connected to the incident? Who is responsible, and why? And will a new incident occur?