It's one of those sort of dating sim touching games, although the touching here actually leads to what you want it too. This game had a sequel, which focused heavily on oral stuff, but this one is definitely sexual in nature. There's not much story to go on, as your basically just trying to strip nude this aquatic princess and have your way with her.
Graphically, the game is pretty amazing. Just the right amount of sexy bouncy curves that you would expect, and there's plenty of naughty things to be seen. The game progresses through Chapters, which advance when you read a certain erotic level, with the next Chapter unlocked more risque things. Here's where things get kind of annoying though.
To raise her sexual levels, you have to massage or grope various areas on the sea unicorn princess gal, which also builds up points, that you can spend to unlock new items or techniques. However, after the first few stages, you go from getting chunks of percent a second, to literally a fraction of a percent per click. Frankly, it gets really tedious.
That aside, the game is plenty sexy, but if your going to play it, I recommend using cheats, and just going through the normal story for a short while before skipping ahead, if your dead set on "earning" the final rewards, as the game isn't very long content-wise, but it could literally take you an hour just to advance the game one Chapter.