Phantasm Calculus

The Phantasm Calculus (幻結石,) or Illusion Calculus, is a calculus the produces illusions.

Appearance
Unlike the Life and Nil Calculus, the phantasm calculus is shaped as two straight bones joined unevenly parallel together.

Background
It has been handed down in Yashima since ancient times.

Powers

 * Illusion: It allows Yashima to be invisible to the outside world and unrecognizable to them.