(Asami Sekiya) - Your Dog
* there's a lot of hentai sex but there is a plot, its kind of like a twisted romance.

Cheerism
* Also has sex, but a couple of the oneshots are kind of cute. Sorta. lol

"How do you always find an excuse to get spontaneously naked!!"

            - Absolute Boyfriend

Seconding Nana to Kaoru and Sundome.

Eroge are games. Maybe he's looking for game-adapted manga?

Quote from coffee_11

Eroge are games. Maybe he's looking for game-adapted manga?

Maybe. At the same time, what's a "borderline eroge"? It's either eroge or not; sexual content or not. There ain't no borderline.

If that's the case, however, here's some categories:

Based on a Visual Novel
Based on an Eroge

Though I'm pretty sure he meant "borderline H".

Surprisingly i found Himitsu no Akuma-chan to have a very enjoyable story.

Personally I don't think there is a borderline hentai manga with a great plot. All stuff mentioned can have at most a decent-mediocre plot, but I can't really say that they're great. I'd only define as great some early parts/chapters of Kodomo no Jikan, but that manga is not everybody's cup of tea.
If you want something like Nana to Kaoru, you should try something like Yuria 100 Shiki (which is the funniest of the bunch imho), Oretama, Kanojo wa Kanno Shosetsuka. Something more elaborate in term of plot and less sex related could be Kangoku Gakuen. Hope this helps.

What I like in Trivial Pursuit style. Pick your category:[img]http://i379.photobucket.com/albums/oo233/Reid4891/Manga/trivia-1.jpg[/img]

Thirding Nana and Sundome, especially Sundome!

This thread is pretty old, yeah? But I did recently finish My two wings and it was alright. I read like two chapters of Nozoki ana, it was ok I would have continued with it if I didn't dislike the main couple.

how do you define great plot with a hentai manga?