I noticed one of the alternate titles is Freak. And if you notice in the synopsis the cops question their own motives... Spells out to me someone with a disassociated personality.
We Japanese dorama lovers have an unfortunate fate in that there just are so few subbers in existence! I feel your your pain as I invested in two whose final episodes remain without subs. Given that they were both excellent it is most frustrating. I feel poorly for the actors who won’t get the international exposure owed them.
eng subs