Kuuchuu Gunkan Atlantis

Set on a floating island called Atlantis, the story follows a captured girl named Luna and her would-be rescuer Cyan. Not everything is a simple as it appears thanks to a mysterious enemy and the robot Gekiga-go.
(Source: Goboiano) Note: A 15 minute film, homage to GAINAX works, produced by Gekigadan, a group of 30 college students from Kyoto.