As Fujiko goes undercover as a tutor looking after some children in order to get some world treasures on a train, including the successor to a country, she meets the samurai, Goemon Ishikawa XIII, who is on a mission to assassinate the children's grandfather, Mr. Trunc. When the assassin wants to kill both Trunc and Goemon by sending the train out of control, Fujiko and Goemon work together to save the children by separating the passengers from the treasures.