Futari Ecchi
Manga Sutra
ふたりエッチ
An excellent and very educational series. About a newlywed couple who are virgins and their comedic ups and downs in learning how to have sex. Not really a hentai, though there are scenes which can be called hentai. Tastefully rendered taboo themes. A funny "how to" guide for sex illiterate and experts.
(Source: MU)