Dimension High School

Junpei finds a rock and brings it to his tutoring class, where it awakens as Spudio, a messenger from Oedipus.

Yurio is hiding a secret from Tsuyoshi; Tsuyoshi confides in Junpei about how Yurio had saved him from a motorcycle accident a year ago.

Determined to bring Tsuyoshi back, Yurio studies and prepares for battle with the Sphinx; when the remaining group solves both puzzles in a row, Paramesos is defeated and Tsuyoshi returns.

While waiting for tutoring, Spudio transports Junpei, Ryusei, and Tsuyoshi to battle with Sphinx Dictis; when they run out of time for the first puzzle, Ryusei is eaten, but Junpei solves the second puzzle, causing him to return.

When Dictis faces the four students, Junpei solves both questions in a row, defeating him and restoring Ryusei's arrogant personality.

Junpei is hailed as a genius while he befriends everyone, but he wakes up to realise it was all a dream.