Tokyo. The maple leaves will soon turn yellow. Tomoyuki Kawayama, a detective for the Tokyo Metropolitan Police, is thinking about taking an annual trip with his wife, Mizuko, to a mountain hot spring-onsen-to enjoy the changing of the leaves-koyou-when his chief tells him to go to a Kabuki-cho love hotel to investigate the death of a young woman. Though a seasoned detective, nothing has prepared him for what he is about to learn...