Matantei Ragnarok

Summary: 

    The main character is Loki, the Norse god of mischief. After causing boundless trouble in the land of the gods, Loki is banished to the world of humans and transformed into a childhood version of himself. To get home, he must collect "evil auras" (evil spirits), so he sets up Enjaku Detective Agency, specializing in strange and paranormal cases to make his search easier. For better or worse, he attracts Mayura Daidouji— a mystery-crazed teenage girl who quickly appoints herself a member of his detective agency. Soon more gods come down to the human world to kill Loki under Odin's order.

The series is based upon Norse mythology, but with many artistic liberties taken with the source material for the manga, and many further changes made from the manga to the anime.