Neuro (Majin Tantei Nogami Neuro)
The series focuses on Neuro Nōgami, a demon who eats mysteries and puzzles. Because he already ate every mystery in the demon world he comes to our world to feast on the mysteries offered by humans (who release negative energy from their planned crimes). As a demon, he must not make his presence noticed by the humans as it is the law in the human world. Because of this, he makes a deal with high school girl Yako Katsuragi, who has her own mystery to solve, and together they solve crimes for Neuro's appetite. After solving many crimes, a case causes a criminal named X to take an interest in Neuro as a demon. Nonetheless Neuro accepts his challenges and defeats him easily. Later on, an evil organization of super humans led by Sicks initiate their plans to destroy the human race. Neuro is able to defeat the organization members one by one, but is severely weakened as a result. He returns to the demon world to recover from all his injuries and returns to the Human World three years later (and meets up with Yako again).