Ingari are said to be the vengeful spirits of departed souls who remained trapped on earth after their passing. In Ingari lore, only pure souls are granted access to the afterlife. Tainted souls are banished to earth to walk among the living, unseen, in a hellish purgatory. An Ingari can atone for its sins and regain access to the afterlife, though it’s incredibly rare for one to do so. Living trapped between two realms often exacerbates the desire to cause chaos and destruction, and thus most Ingari remain on earth eternally.

Ingari can take many forms but are divided into two categories: imperial and ronin.

Imperial Ingari are reptilian-looking and considered the more aggressive of the two. Imperials seek to cause as much pain and suffering as possible, often indiscriminately. It’s said that the sound of their screech is a sign of certain death. Imperials are most often the spirits of royalty, military, criminals, and the upper class. It is rumored that some samurai believed ritual suicide would exonerate them from their sins and prevent themselves and their descendants from becoming Ingari, but all who shared this fate were transmogrified into Ingari as a result.

Ronin Ingari often possess more mammalian traits. Unlike Imperials, Ronin are not outwardly aggressive. They have little interest in harming the living, but do enjoy playing pranks and causing chaos, many of which have ended up causing injuries and fatalities regardless of their intentions. Ronin are most often the spirits of average citizens, children, the poor, and the abused. Their harbored resentment of those who have wronged them rendered them unable to gain access to the afterlife.

In order to physically see an Ingari, a mitama (often called a “soul bead” by foreigners) is needed. Post-war revenge killings executed by Ingari became so pervasive that mitama emblems were then expeditiously incorporated into jewelry, clothing, furniture, decor, children’s toys, and other such knickknacks. While only certain mitama are imbued with the power to reveal hidden Ingari, the emblem itself is considered to be a warning sign to the spirits in an effort to deter them. While mitama are usually enough to drive Ingari away, the only guaranteed method of protecting oneself is by destroying the Ingari's chitinous helmet.