 If you liked
Kara no Kyoukai Movie 1: Fukan Fuukei
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 ...then you might like
Mirai Nikki (TV)
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Both are very dark thrillers with lots of action/violence and contain supernatural elements. Both female leads are of questionable sanity and develop feelings for the male protagonist.
They're both really dark and do not shy away from themes such as murder, suicide, and insanity. Kara no Kyoukai is quite a bit darker and more serious than Mirai Nikki, but I think anyone who enjoyed Mirai Nikki for its characters will find a lot to like about Kara no Kyoukai.
It's a bit of a slow burner, but it's worth it if you give it a chance.