Tokinada Tsunayashiro created a specimen from the souls of countless Fullbringers... one capable of replacing the Soul King.

The Hollow contained too many souls to purify at once, leading Å etsu Nimaiya, pioneer of the ZanpakutÅ , to seal it away into a sword which was then renamed Ikomikidomoe through Ichimonji ...

Ikomikidomoe is the name given to a Zanpakuto that has been hidden by Soul Society for aeons, made from a primordial Hollow with no name. Shinji Hirako and the others were all high-ranking members ...