Ninja Kids!!!: Summer Mission Impossible (2013)

At a time when nations are warring, a sword with mysterious power called "Heaven's Sword" is stolen. The sword gives the bearer the power to conquer the world! Rantaro attends the Ninja Academy where he hopes to become an elite ninja. He and his classmates are assigned to retrieve the stolen sword, their first real ninja mission! As an incentive, it's proposed that the kids will have no schoolwork during the winter holidays if they succeed in the mission AND finish their summer homework in time! Rantaro and the classmates help each other and manage to retrieve the sword but fail to complete their homework. To the disappointed kids the teachers tell that all their homework assignments were included in the sword mission! Hooray! The ninja kids scream with joy!