The headmaster suddenly came up with the idea of having the fifth and sixth graders compete against each other in a showdown of their abilities! The winner is the one who finds the treasure that has been decided upon, and the three chosen for the treasure are first-year students Rantaro, Kirimaru, and Shinbee. Finally, the showdown between the sparking fifth and sixth graders began, but a suspicious shadow was approaching the treasured first grader...

Musical Nintama Rantaro's 13th installment's ninjutsu academy school festival.

Dokutake Navy ship suddenly appears, and sink the Hyōgo Pirates Crew's boat. After hearing the report, feeling something's not right, the Headmaster gives the fifth-years an important mission. The fifth-years leave Ninjutsu Academy with excitement of their first mission, but fail, and a rumor of the fifth-years are weak spread around the sixth and first years, and Hyōgo Pirates Crew. Even though they feel their upperclassman think they are "Unreliable fifth-years!", the fifth-years continue the mission in their own way, and went on attack Dokutake Navy ship! Inside the ship, are the trap the endanger the fifth-years and the Pirates Crew!

The 9th installment for the Nintama Rantarou musical.

This is the story of "a certain three days" in their everyday life that seemed like nothing but was special. Would you like to take a peek into their lives as they laugh with their friends and grow a little?