Aoi witnessed Kosaka pursuing Amakusa.

Amakusa said that the person who killed Kosaka's junior detective Aso was not him, but maybe the senior of a special fraud group who killed “ the detective”.

Aoi was worried that Kosaka would pursue Aso's murderer alone, so she sent Natsume to monitor Kosaka.Kosaka decided to risk everything to find out the truth about Aso's death.

Aoi left a note at the scene of the serial murder case, which contained a coded message for the murderer.Aoi originally planned to use herself as bait to lure the murderer to her.

Based on information from Amakusa, Kosaka arrested Sakai, a member of the special fraud group.Sakai said that he only heard rumors that a man who called himself “Hulk” said “killed the detective”.

On the other hand, Fuwa visits Ide, a classmate of the high school culture festival executive committee and a grocery store owner.

Aoi goes to the crime scene and confirms that the message left behind is gone.Someone is following Aoi who left there——!?