Majin Tantei Nougami Neuro
Private Evil-Eye Nougami Neuro
Genre: Detective, supernatural
Premier: October 2007
Manga Official Website: Nougami Neuro
Animation Studio: Madhouse (That's what I have heard, but I haven't seen it listed in Madhouse project)
Original Manga Author: Matsui Yusei
Yako Katsuragi's father was murdered in a locked room. The mystery plunges Yako's life into chaos until she meets a man named Neuro Nougami.
Neuro the Evil can eat only the "mystery" contrived by man's malice,who has been seeking "the ultimate mystery" which satisfies his brain's hunger eternally. But he can't publicly solve mysteries, because he's from the world downstairs. So he forces Yako to act the part of a detective, while he does all the real solving....
There is a fan-made flash animation of the OP if you are interested. It is available here.
Characters: (I only put the two main characters, too lazy to put all to them here)
Manga Covers:(Since the pics are small, I cannot post thumbnails for it)