I think this is the first manga with a hetero couple that has quite explicit sex

theres the whole erotic fairy tales series, along with a few others.. trust me i would know.. ;P

but i'm enjoying this series so far, their work is great. i love how they don't hold back.

seriously??? could you please tell me some title? :3 :3

I think she's talking about this:
http://www.mangago.zone/read-manga/erotic_fairy_tales_the_little_mermaid/
And the other by the same author... :)

Try this tag too, If youre interested:
http://www.mangago.zone/tag/Hentai/