The Ninjutsu Academy pupils return from their summer recess only to learn that, because of a blunder by Komatsuda, every student"s seasonal assignments have been jumbled. Consequently Kisanta, who was given a task intended for the sixth grade, vanished after attempting to infiltrate Oomagatoki Castle in order to pilfer the lord"s fundoshi. A rescue party featuring Shinbei and Kirimaru is dispatched, yet with Oomagatoki currently engaged in hostilities against Tasogaredoki Castle, the operation promises to be perilous.
Simultaneously, the academy receives a plea for aid from a war‑suffering village; Rantarou along with the remaining pupils and instructors departs to render assistance together in hopes of restoring peace for all.