Must read ero-manga?

Haven't been active lately. Reason being I don't know what manga is nice.
So far what I could recall to be a must read are:
Slut Girl
TayuTayu
Retake (Evangelion)

also, preferably those with more than 1 book.

hmmm.... Petit Roid by Tomohiro Kouda, 3 volume.
Parabellum by Nagare Ippon, 2 volume so far.
Purimu no Nikki by Nico-Pun-Nise, about 2 volume.