The rpg takes place in the world of 16th century Japan where yokai exist. Yokai and humans are enemies, because of humans beliefs of yokai being hostile and cruel (which is not always true). Because of that, yokai are forced to hide deep in the forest so no human can hunt them down.

There are such yokai species as: Kitsune (a humanoid oni with fox ears and 4 fox tails), Centepidemon (an oni with human head and centipide body, has 40 hands instead of centipide legs), Oni (humanoid demons) 