Arthur scratched his neck, doing his best to follow along, but now a bit confused. So regret on the part of the victim?

"So...if someone's murdered but the victim is feelin' regret either regardin' their killer or towards...something else, they become a mononoke?" he asked trying to nail it down.

He shook his head at that. "No, not at all, I just tryin' to figure how these creatures come into being..." he paused then snorted dryly, "And wonderin' if old Dutch...or even myself might have left some behind in our time."