A menreiki (面霊気, roughly "mask essence") is a type of youkai in Japanese folklore, composed of Gigaku masks.
Menreiki in Touhou
In the Touhou Project, menreiki are more akin to the collective tsukumogami of a mask. There isn't much information on their powers, exceptional strengths, or ways to defeat them. The only example of a menreiki in Gensokyo is Hata no Kokoro, the tsukumogami of a set of masks once created by Toyosatomimi no Miko. Being recently born, there isn't much known about her beyond what's revealed in Hopeless Masquerade. Her masks were her way of expressing and possessing emotions and if she loses even one, there's the risk of the others going out of control; the main plot of Hopeless Masquerade centers on this. She appears innately skillful in various Noh plays.
Characters under this Bestiary