I've been thinking about it for a while. Why did Kurohagane look like Hotsuma following restoring Akujiki's sword form? In PXZ2 Hotsuma sees him and gets very uncomfortable, and each time there is something he felt was not right with him. Is it possible that Kurohagane IS Hotsuma's corpse turned Cyborg? After all, Hotsuma died after killing Hiruko so that he could free himself of Akujiki's grasp.