|(観月秀理, Mizuki Hidemichi)|
|Appears in||Manga only|
Hidemichi Mizuki (観月秀理, Mizuki Hidemichi) was a high school teacher, few years ago. He passed away in a flat where he lived in in Haidō City. He was also the teacher of the serial killer Kiriya Hido. The police force protected Mizuki because they where afraid that Mizuki could be killed by his former student Kiriya. He killed himself by hanging himself up which he put the rope at his air conditioner. Heiji, Kazuha and Gorō though that he has been killed by a killer which makes them think that he pledge suicide. After that his case was solved, they think that Fūra was the one that made it happen after that Hidemichi had stacked up a huge dept from buying and selling shares which he also has a extremely big grudge against Fūra which he said in a bar that he must drag down to hell.