Girls Paradise Rakuen no Tenshi-tachi

The protagonist of the game is an eighteen-year-old boy whose destiny is to defeat a legendary demon, thus ending the Age of Darkness. As the hero embarks on his journey, he realizes that he must have chosen a wrong destination, for he becomes stranded on a tropical island that seems to be populated entirely by women. No, the hero does not abandon his world-saving mission because of that; but in order to leave the island, he needs to perform various quests for its young and pretty female inhabitants, which more often than not involve demonstrating... err... somewhat intimate aspects of his heroic nature.

[From Moby Games]