Cybernetic Hi-School Part 3 ~Top o Nerae!~

You, as an alpha-class Top, are supposed to win three keys to pilot the Great Gunbuster robot against the cosmic threat to humanity. The keys are held by Jung-Freud, Kazumi (oneesama) and Noriko, and you must retrieve the keys by defeating each character in a quiz game, which has the side-effect of stripping them of all their clothes.

[From Moby Games]