I think Oono is bait, not Kashin Koji. Pretty sure Oono & Kawado are guards. I swear somewhere back in the earlier days of the series, might have been Kuro talking to somebody about KK. Something about KK, the Kumogakure Clan, and 2 other "guards" or special NIN that were with KK or something. Need to go back and reread some parts I guess. My money is still on, the still pretty much unseen landlord. Definitely could be wrong. But to me, in this series, it just doesn't really fit the narrative or style of storytelling to have something so important spelled right out and played so "on the nose."