The book is set between B and Y, which is 32 and 33. Shotaro has fallen sick from a cold, and Philip decides that he will accept the cases until Shotaro feels better. Shotaro says that he feels like a zombie, which is further hinting at the Z in the title. Philip takes it so far that even uses Shotaro’s name and tries to act like him. Philip even starts wearing a hat, but instead of a fedora he wears a flat cap. Terui appears and ends up playing along with Philip, at one point when Terui is calling for Philip, Terui says “Hey, Phi… Phidari…”