Hello!

I'm looking for shoujo or josei mangas where the story is filled with a lot of drama. It can make my cry or feel sad or make me think of serious issues about the life and world.
E.g. Six Half
I'd like to read something which has a dark atmosphere. It can be really dark, I don't mind e.g. Bokura no Koi wa Shi ni Itaru Yamai no You de

Thank you for all your suggestions!

Mars
Kare Kano
Kimi wa Petto
100% Perfect Girl
Snow Drop
Annarasumanara
Flowers of Evil
NG Life
Boku no Hatsukoi o Kimi ni Sasagu


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I don't know about 'dark' but Orange will definitely make you you cry

You mean Orange (TAKANO Ichigo), right? Good manga.

Similar mangas to Six Half:
Forget About Love
Oboreru Knife
Yumenara Samenaide
Midnight Children
Atashi wa Sore wo Gaman Dekinai

oh yeah, my mistake, sorry. That's the right one

Hmmm, your lists are private/non-existant, so I may just be repeating the obvious

Koizora - It is everything you asked for and more
Kyou no Kira-kun - Not particularly sad (yet) but it's building up
Mademoiselle Butterfly -If you haven't read this, READ IT NOW!!
Amakusa 1637 - I don't know how you feel about fantasy, but this is a great one. In saying that it is fantasy, the only fantasy element is time travel.
Bokura ga Ita - This has it's moments in terms of drama and dealing with serious issues, but at the same time, i felt given the narrative it was quite idealistic

I also suggest Usagi Drop and My Girl (SAHARA Mizu). Although the latter is considered a Seinen, I absolutely enjoyed them both.

I also think Oboreru Knife, Mars, Kare Kano, Snow Drop and Boku no Hatsukoi o Kimi ni sasagu would be right up your ally as previously mentioned

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My Blog: http://himexcherry.blogspot.com.au/

Oboreru Knife
Mademoiselle Butterfly
Bokura Ga ita - my favorite!
Tobenai Tori - actually, I don't really like this one, but, it's fit enough.