shibe since their is two imposter currently suspension is on tenji or shibe. I bet the other one is shibe unwillingly (or not) or the men himself Yuuichi but back to shibe and reasons I have proof to back up my accusation, 1. remember how they mentioned the calculations didn't add up? it absolutely can't not be tenji since he showed his numbers in the cave with yuuichi and we as the viewer witness the number of his debt doubled. 2) also remember how the hit men said he killed Tenjin father but theirs's no mention of how shibe father was murdered? they believed that shiho's father was involved but everything was revealed about him and shiho so who really did killed shibe's father? or did shibe murdered his dad himself or somehow witnessed it ?.............. all and all in the back of my mind I also think yuuichi is also orchestrating the whole thing not in the sense of being the traitor but knowing who's really behind all this form mid story.