Devil's Eye is a type of Mystic Eye that allows the user to place all their wishes into a special eyepatch which they use to seal the power contained within the eye. The only known user of the Devil's Eye is Yagyū.
It is implied that Devil's Eye can vary from person to person and thus different people can have a different Devil's Eye.
- Yagyū: In Yagyū's case, her eyepatch is made of normal material and her deceased sister's ribbon. Within time her eye behind the eyepatch began to turn her memories of her sister into raw power.