Aku no Hadou ~ Satsujin Bunseki-han Spin-off

In 2014, a series of murders targeting women takes place in Kawasaki City. All the victims have been killed as if they had hanged and these are dubbed the "Hanging Murders" in public. The police investigation runs into difficulties without clues on the murderer. However, Detective Iguchi from the First Investigation Division has his eye on a man whom he suspects to kill for pleasure. This man is Naoya Nogi. He lies about his identity, erases his traces in public, and lives as if he is holding his breath. Nogi is actually Masato Yaginuma, the victim in the sensational Akishima mother and son kidnapping case. He gets his neighbor, Yoshika, involved as he tries to escape the police dragnet but comes to realize some facts. What is his true motive?