User blog comment:Xilinoc/Ch. 579 - THE UNDEAD 6/@comment-6916556-20140507185035

I reckon that Yachiru is a part of Nozarashi. The last time we see her is before it releases. She has a flashback with Kenny asking if she has a name, and he says he doesn't either. The next panel he releases Nozarashi. That is the *last* time we see her.

Now her robes are lying on the ground. She wouldn't be naked.

We also know her shikai isn't typical of anything Isane has ever seen. It summons to creatures, not manifests from within but physical summons two creatures. Isane said this isn't what the shikai should/can do.

I think that Nozarashi projected Yachiru after a big massacre of Kenny's to keep him company, but now he knows Nozarashi's name, it is no longer needed, and she returned to Nozarashi after he is released. She accepted Yachiru because it was the name of the only person that ever made Kenpachi and therefore nozarashi happy.

I know that Zan spirits can't have swords, but Yachiru has been noted to have a weird shikai, and her beasts looked hollow like, and we know asauchi/zanpakuto are related to hollows.

It would make sense as to why her robes are left on the ground with no trace of her OR her spiritual pressure. She also always wore a skull and crossbones motif on her hair, and Nozarashi means a motif of skull and bones in Japan.

The female Sternritters would have been noticed by Kenny if they hurt Yachiru and it seems they only turned up at the end of the chapter.

Maybe one of them did have a power, but considering when Yachiru was last seen, her character design, link with names, and indeed odd shikai, I am inclined to think she is some manifestation of Nozarashi. Especially as Nozarashi hasn't acted typical of Zanpakuto (it was constant release shikai yet miraculously changed form upon calling its name).

EDIT: We know Yachiru was alone since we don't see Isane or the captains (alive or dead) with her when she looks at Kenny release.