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!
