The Nadesico has been tasked with defending the moon using its new phase transition cannon, but when something goes wrong with the Y Unit, the weapon becomes inoperable. With only an hour to fix it, the ship's pilots are sent down to traverse the now hazardous corridors leading down to the Y Unit and find out what has happened, a task made all the more difficult by the fact that their minds have become linked together into an illusory ""memory mahjongg"" game, whilst repressed portions of their personalities take control of their bodies...