Seconding
Ghost Hound, very good mystery with elements of horror and supernatural and likable characters.
More recommendations:
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Mouryou no Hako: more people should watch this! A great detective story with elements of horror, complemented by gorgeous visuals and music. Kept me on the edge of my seat during its run, blew my mind when it's finished. (Note that some ep is dialogue-heavy, but stick to it, it's worth it in the end.)
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Himitsu: The Revelation: again, detective story with elements of horror (or should I say: nightmare inducing). Have a very interesting and unique premise, interesting cases, good characters, overall quite enjoying (even though the ending is not to my liking).
And if you can overlook the character designs, try
Fantastic Children. Very interesting but underrated series. Beneath the overall mystery lies a great drama and love story.The pacing is kinda slow though, only picks up around the half way point, but the end result is beautiful and satisfying.