Captain Square is the main theme for the faux arcade game "Captain Square" that can be played inside the distant future chapter, "Mechanical Heart". It plays softly in the break room of the ship where the arcade cab is, and then plays normally for all of the battles within the game.
This song is track 15 on the official soundtrack.
- English: Captain Square
- Japanese: ＣＡＰＴＡＩＮ ＳＱＵＡＲＥ