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...