It's Halloween in the Stone Age, and the villagers are excited. Although no one knows exactly why they dress up and tell stories about ghosts on this day, they enthusiastically follow the new "tradition" that Senku has started. He has explained that it is a "scientifically proven" custom that protects the village from evil spirits, and his enthusiasm has infected everyone, almost everyone. Kohaku and Chrome exchange skeptical looks, but the villagers are excited and have put in their best attempts at making spooky costumes.