Kento is a police officer who was a young boy when a little girl he was friends with was kidnapped and murdered, and he witnessed the mysterious woman who took the little girl away. However, no one took him seriously even when he informed the police. Fifteen years later, the case had gone cold, and the statute of limitations was about to run out. One day, he hears a voice coming from a radio that was supposed to have been thrown away. The voice belonged to a detective who had been investigating the same case, and he told him about a lead in the case. Kento couldn’t believe it at first, but after he went to the place the detective told him about on the radio, he found someone’s skeleton.
As Kento continued to communicate with the detective, he realized that the person he was talking with on the radio was a person who was living in the past. They cooperate with each other to solve cold cases over the mysterious radio.