If you can imagine a school club where, instead of going "Hiiii-ya!" , you go "Ah-Aaaahn~" then you pretty much have the general idea of what this new series by Kisaragi Gunma is about! (commissioned by Oliver from hentairules.net)
Another one from the Mai series. To get to the point. This is smexy. Great art work and great story line. I recommend reading 1 through 4 before reading this so you can follow the story a little better but even if you don't this is a great read. You can get the complete uncensored tankoubon here.