User blog comment:Mrlmm0605/Let's Talk Bleach!: Part 11- Kenpachi Zaraki/@comment-10301320-20160404125809/@comment-10301320-20160405013950

Hmm, I'm of the opinion that Sanpo Kenju's is Yachiru's unique-to-her zanpakuto. I know, that makes no sense, a zanpakuto spirit with a second zanpakuto but there's no precedent for this being possible or not. Giving the likely rules-defying nature of Yachiru as a zanpakuto spirit I wouldn't be surprised if she manifested in a way that her composition is identical to a shinigami, i.e able to imprint upon an asauchi. Unless I'm wrong, I was of the opinion zanpakuto can have their own reiatsu that's theirs alone (I might be wrong about that though, I'm basing it on "Zangetsu" giving his reiatsu to Ichigo during his and Kenny's fight and well that wasn't a zanpakuto), and Yachiru's personality and such is far away enough from Kenny's that her zanpakuto would manifest differently. Then again, you could be right, Occam's razor and all that.