I always read yaoi but i never read a manga that has heterosexual sex. I don't even know ...

http://www.mangago.me/read-manga/diamond_kiss/
http://www.mangago.me/read-manga/anata_ga_watashi_to_kurashitara/

As for genre it would be josei, romance with smut/adult tags. :)

I'm just here for the answers, don't mind me~

http://www.mangago.me/read-manga/haou_airen/
http://www.mangago.me/read-manga/aisuru_hito/
http://www.mangago.me/read-manga/itadakimasu/
These r my faves. Enjoy~ (●'◡'●)ﾉ

Omg same I love yaoi but try shoujo, yet I never found a good one (๑•ㅂ•)و#

http://www.mangago.me/read-manga/h_mate/

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Hentai is explicit porn written with a male demographic in mind. I'm not saying that they don't have some female readers, but for the most part, the content seems to be driven by a male audience. If you're looking for any type of story there, you're looking in the wrong place. I'd suggest shoujo or josei, but look for maybe smut or adult tags if you want there to be some focus on sex like there is in BL.

However, if you do search under smut or adult tags for josei romance, you're likely to get something that's more harlequin-oriented. Shoujo is directed at a younger female audience, but it's open to a wide variety of viewership beyond young females. Most of the time it takes place in a high school setting and depending on the manga-ka, you might get very little to some sexual romance. If it's a longish running shoujo, then you're likely to see some sex but it'll be the culmination of many chapters and not anywhere as constant as BL where you're likely to get sex the first chapter or so. Just depends on how much you're looking for.

I'd suggest NANA by Ai Yazawa for a shoujo/josei series where the sex is naturally integrated into the story and the relationships. It's not nearly as explicit as BL (though you'd be hard-pressed to find that level of graphic or explicit content in any josei or shoujo even under the smut tag). It's a classic series in the genre, but be forewarned, it's not complete, but I'd say it's worth the read regardless. If you like NANA by her, also try out Paradise Kiss.

Also if you're looking to read heterosexual manga where there are more mature relationships, I'd stick to Josei, which has content featuring material that's more "realistic" and not so ideal and light-hearted as shoujo. Though josei doesn't see as much scanlation as shoujo.

I'd also recommend Futago or Six Half by Iketani Rikako, though Six Half has very little to no sexual content at all (in regards to the main couple, anyway).