I don't read a lot of horror because I don't like the genre but I have a lot of thriller...
https://www.mangago.me/read-manga/misu_misou/
This is horror. It's kind of drawn cutely so people can't really take it as horror, but it is horror and it is kind of creepy. The plot itself is kind of meh though.
https://www.mangago.me/read-manga/bastard_hw......
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