Spirit derives from Japanese mythology.
Oni, meaning "to hide or conceal", are a kind of Yōkai that were originally invisible spirits or gods which caused unpleasant things.
Oni are born when truly wicked humans die and end up in one of the numerous Buddhist hells then transformed into Oni.
Oni is a name used for male demons and Kijo is a name used for female demons.
Occasionally, a human can be so profoundly wicked that his soul is unable to reach redemption, he can transform into an Oni during life and just remains on Earth to terrorize the living.
Forbiddens are very aggressive that can attack everything - including summoner and allies.
Summoning ingredients requires: Calamus Root and Iron Lock