Zai

"I am Lord Kaguya!"

Zai is the main servant of Muzai. Once his little sister, massacred, in a fit of rage and depression, Muzai's chakra bonded to her bones; resulting in a servant filled with most of his energy. Meaning she has a wider use than his other creations. Muzai relies on Zai on more task than others. With such a heavy influence of Muzai, being created from his large energy source, Zai's loyalty goes unrivaled. She is Muzai in a sense. All his memories, experiences run through her body. She is no longer the human she once graced the earth as.

Background
Born as his little sister.... Killed... In anger Muzai's chakra bonded to her bones...