Ryusei invites everyone to a puzzle-solving game, to which they confirm that Junpei has lost his puzzle-solving abilities. When they are summoned to the dimensional classroom, the Sphinxes, using Mr. Momoya as an avatar, engage them a battle. Junpei wagers a challenge, offering all four of their lives if they lose the battle. However, if the Sphinxes are unable to solve a puzzle the students give them, they will leave the third dimension alone.