*jingle jingle*

I think Kanako had plenty of choices when it came to choosing someone to run a nuclear furnace for her. However, instead of a regular hell raven she may or may not have been able to talk with in the first place being an animal, why not an oni. Suika's off doing her own thing, Kasen's a hermit, the fourth deva is yet to be heard from, and Yuugi's still down in former hell. I think Kanako could have promised Yuugi greater power and glory to former hell if she were to absorb part of the Yatagarasu's soul. No oni would turn down such an offer. Strength is power. Doing so significantly exposed Yuugi to radiation and permanently fucked her up physically, but she effectively comes out of the other end an unnatural asura.