what happened to yachiru

Yachiru Kusajishi was Kenpachi Zarakis Lieutenant in Bleach. She was a small girl who loved Kenpachi very much and was always by his side to aid him or cheer him on. However, she disappeared under mysterious circumstances during the Thousand Year Blood War. According to the Wikia, Yachiru disappeared leaving her belongings after the fight with Gremmy. She is said to be "gone" by Kenpachi in the manga. It is assumed that she would disappear while Kenpachi would use Shikai or Bankai. In Chapter 579, she simply faded away, leaving behind her uniform and badge. Her disappearance coincided with Kenpachi's defeat of the Quincy Gremmy, but there was no good explanation for what had happened to her. Then, in Chapter 668, Yachiru seemingly reappeared to Kenpachi as he laid on the ground near death, after attempting to fight the Quincy Gerard Valkyrie. Answering one of the fans' questions, Tite Kubu revealed that Yachiru is a part of Kenpachi's Zanpkuto, Nozarashi, and she got separated from it. Therefore, it is implied that Yachiru was just a manifestation of Kenpachi's Zanpakuto and that she wasn’t real.