I just finished reading the first 3 chapters of this Shonen Jump Mystery called Majin Tantei Nougami Neuro (Demon Detective Nougami Neuro). It's about this demon detective who comes to this world to feed on "riddles", he approched this one girl (Yako) who's father has just been murdered and offers to solve the case. It's a neat blend of dark humor, mystery, and demons. I recomend it to people who like mysteries (like myself ^_^)
You can dl the first 3 chapters here: http://www.punkednoodle.com/mangacurry/