Nintama Rantarou Movie: Ninjutsu Gakuen Zenin Shutsudou! no Dan

When the students of Ninjutsu Academy return from summer break, they discover that Komatsuda accidentally mixed up everyone's homework assignments. The mistake has serious consequences: Kisanta received a task intended for a sixth-year student and has vanished after attempting to infiltrate Oomagatoki Castle and steal its lord's fundoshi.

A rescue party heads after him, only to find the castle caught in a war with Tasogaredoki. At the same time, another request reaches the academy from a village suffering because of the fighting. Students and teachers are soon scattered across both problems, turning a ridiculous homework error into a mission that calls nearly the entire academy into action.