Based on the shounen manga by Matsui Yuusei serialised in Weekly Shounen Jump.Neuro is a being from the underworld, who likes to eat “riddles” and “mysteries” and since he had heard that mysteries abound in the world above, he comes surface side in search of the ultimate riddle capable of satisfying his insatiable hunger. He arrives in front of Katsuragi Yako whose father has been murdered, and smells a tasty riddle…He agrees to help her to solve the murder of her father and in turn forces Yako to act as a detective in his stead, always searching for the ultimate riddle.