one-sided love

Dark heaven is pretty tragic and sad(ish) it deals with a lot of drug use and violence aswell as rape but overall it’s a great story, I adore it so much! But if your sensitive to any of the following I would not suggest to read it

http://www.mangago.me/read-manga/sachiiro_no_one_room/
It's called Happiness in One Room and it's a sad shoujo story. It's about a girl who's kidnapped by a person who doesn't want her to die because she was going to commit suicide. So it's them trying to not get found out by the police and her returning back to her "family". It's very different from regular shoujo mangas.

Yaoi manga
http://www.mangago.me/read-manga/hitotsu_shikanai_mono/
..... mostly about self healing but has one sided love
http://www.mangago.me/read-manga/me_wo_tojite_yume_wo_miru/
....... a lot of smut , rape and prostitution and age gap
http://www.mangago.me/read-manga/maki_chan_wa_kare_to_sex_shitai/
...rape , depressing
http://www.mangago.me/read-manga/kosha_ura_no_natsu/
.. tragedy this one might make you cry
http://www.mangago.me/read-manga/kokoro_o_korosu_houhou/
..DARK SOOOO DARK has smut , rape and twisted (this is my favorite though )
http://www.mangago.me/read-manga/cut/
..... sad past for both mc , incest ( kinda of incest bcuz it was his stepdad) but it has a good ending
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Shoujo
http://www.mangago.me/read-manga/flowers_of_evil/
...tragedy , incest and dark ( and has a plot twist )
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That's all I have now. I hope you like them
Sorry I have a wierd taste