Since the times of ancient Japan, a mechanical rice dragon was built each year as an ingenious sacrifice and hope for a good harvest. One day, a dictatorial General bids Sanshu to build a new mechanical dragon, but is refused when the builder realizes that it will be used for evil purposes. So the General kidnaps the builder's daughter to force him to build, then refuses to release her because he wants to marry her. The rice dragon then takes on a life of its own and the Heap must put an end to it.