Holy shit this turned into something I really did not expect considering this is a S&M Manga. This is soo fricking good I literally thought it would just be S&M and I kind of hesitated to read this Manga but damn I'm glad I was wrong, It really had an amazing way of story telling that I did not expect from S&M Manga. Nana to Kaoru obviously have eroticism and naughty stuff on it considering its an S&M ecchi Manga but that doesn't really take off the excellent characters and the storytelling aspect of this Manga, it may not be for all the Manga readers out there but please give this Manga a shot because its really good.
Overall: 9/10 or a 10/10
I'm leaving this short review for nostalgia purposes.