I obviously didn't watch it for the plot. Although the plot had great potential, too bad they ended it without a solution, just as it was getting interesting. The manga has more of the plot, but it's as incomplete. The sex scenes desperately lack imagination (and probably experience of the author). They seem copy-pasted from one episode to another, with little variety. The female character lacked everything personality-wise, but it worked for bdsm anyway. The advantage of the anime is that it doesn't have many competitors that would cover the same theme, to be compared. All-in-all, if you're watching this for the purpose it was made - ithink it works very well. Enjoy!