User blog comment:Xilinoc/Ch. 668 - BIGGER,FASTER,STRONGER/@comment-1268838-20160331160224

Well, it seemed kind of obvious that this was the case since her disappearance. Sure, we never had confirmation, but just like with Gin being a filthy stinking traitor, and (cross-series reference) Tobi being Obito, the truth is so freaking obvious, even with an absence of evidence.

Now, contrary to everybody that must be raging right now, I don't really have a problem with her being his Zanpakuto spirit, odd as that might be. We know that physical manifestation is a thing; with Zaraki being as exceptional of an individual as he is, I am not surprised that he has broken several rules. Bleach is as consistent as it is fraught with exceptions to its own rules, especially when it comes to characters like Ichigo and Kenpachi.

As for acquiring Bankai on the other hand... egh. I dunno. Someone else commented on another forum that Zaraki basically went through the steps of acquiring it backwards. If Yachiru, his subordinate, truly IS his Zanpakuto spirit, then he has already passed the manifestation and subjugation stages, albeit unintentionally. Frankly, we have never even seen the process of a Bankai being acquired through natural means before, making this even more complicated. It still feels odd for it to be just slapped onto him like this, but whatever.

I predict that the next chapter will be a retrospective of how Yachiru came to be, how she became a freaking Shinigami for that matter, and how this all ties to the limitations Zaraki applied to his own power. In true Kubo fashion, he will actually use it at the end of the chapter.

It could be worse, guys. She could be his Hollow powers instead. :|