Title: Elemental O
Company: Apple Pie
Format: 1 HDI image
Size: 5.05 MB Compressed
Game Type: RPG
Adult Content: Nudity, Sex (Censored)

Your main character looks like he should be in Pokemon rather than a hentai game, but this is most certainly a hentai game. You defeat a number of female opponents and do X-rated things to them. I couldn't manage to get to the first battle, so I'm not sure if it is card based or what.

You can find a more detailed description on MobyGames.