This game is old. Like really old. Like more than 15 years old. So, there are going to be some things that aren't... optimal... about it. If you are old enough to remember 15 years ago, you might also be old enough to remember "Hong Kong Mahjong" style matching games. If you don't know what that is, it is a game that uses tiles from Mahjong (basically East Asian poker), but just as a matching game with a few restrictions on which tiles you are allowed to match, when you are allowed to match them, and nuances to the scoring. It looks complicated, but it's pretty much the equivalent of comparing "Go Fish" or Solitaire to Texas Hold 'em.
The music is surprisingly nice, the translation is poor to the point of being nonsensical, and the sex is just... kinda there for no reason. Honestly, it's almost a shame the game is NSFW, because it would otherwise be fun to play during a lunch break (and the sex doesn't really feel all that sexy anyway).
A marginal familiarity with the kanji for numbers makes playing this game a bit easier, so here you are:
1. 一 (ichi)
2. 二 (ni)
3. 三 (san)
4. 四 (shi/yon)
5. 五 (go)
6. 六 (roku)