Nana to Kaoru, oddly enough, is a look into proper, Real Life BDSM. It includes things you tend not to see, like the fact that it doesn't have to be about sex. Care and attention has been shown, not only for the idea of prep work, but the psychological aspects have been shown as well. There is no pain without wanting to go there, and limits are gradually pushed.

In short, this is a must read for anyone that has the wrong ideas about what BDSM is.