The father of high school student, Katsuragi Yako, has been brutally murdered. The incident filled with mysteries drives Yako's daily life into confusion... As the investigation progresses slowly, a man named Nougami Neuro appears before Yako saying that he wants to eat the ultimate "riddle"...! The Demon Neuro has a raging hunger for ‘mysteries.’ Being dissatisfied with his current regime in hell, he’s come into the mortal realm in order to satiate his ever-growing appetite. The murder case of a young girl’s father seems to be sufficiently enticing for the Demon’s needs... But what else might happen between these two?
