Tokei Tokinomiya

A mysterious person that is able to make puppets out of people to do its bidding. Tokei is also capable of disguising herself as others, but requires a catalyst that will allow Tokei to do so.

Tokei disguises as Jun Aikawa and battles against Soushiki, but ultimately dies after the illusion is broken. It's revealed that Tokei is actually an elderly woman.
It's later revealed that Tokei may have killed Yumiya Sawarabi, via disguising herself as Hitoshiki Zerozaki.