Spirits on Lenguri, commonly referred to as "yokai", all come from the Mirror World, being the transformed souls of those who died--whether it be the souls of mortals, beasts, or anything else--changed into new forms. Yokai can only come to Acirena through gaps between the Mirror World and Acirena, which Lenguri has many; these gaps, known as the "spirit veil", are often mysterious places, such as giant forests where fog and mist seem to call your name, or graveyards that have shadows dancing around in the moonlight. However, one type of yokai, called the "oni", come not from the Mirror World, but rather from the Underworld, being the souls of evil beings that escaped the Underworld's grasp, and live in the Mirror World, until they pass through a spirit veil. Most oni still have a portion of their mortal personality, such as a gluttonous orc becoming a type of oni obsessed with eating.