User blog comment:Xilinoc/Ch. 668 - BIGGER,FASTER,STRONGER/@comment-27001684-20160331140108

Yachiru may meant by using "her", that she is able to transfer her power to Zaraki in order to make him able to use his Bankai without proper training, Kenpachi already met Nozarashi, "HE" told him his name after all and Zaraki can most likely enter his inner world after achieving Shikai. Yachiru also may be ONLY a part of his Zanpakutou.