In traditional beliefs and Japanese literature, onryō (怨霊, literally "avenging spirit," sometimes rendered as "wrathful spirit") refers to a deity (yūrei) supposedly capable of causing harm in the world of the living,

harming or killing enemies, or even causing natural disasters by exacting vengeance to right wrongs received while alive and then taking over the spirits of the dead bodies of enemies.

The term overlaps somewhat with goryō (御霊), except that in the cult of goryō it is not necessary that the agent acting be a wrathful spirit.

Origin of the onryō

Although the origin of the onryō is unclear, their existence, which dates back to the seventh century, is inspired by the idea that the powerful and enraged souls of the dead can influence or harm the living.

The earliest cult of onryō developed around Prince Nagaya who died in 7291 and the earliest record of possession by an onryō spirit affecting health is found in the Shoku Nihongi chronicle (797) which states that "the soul of Fujiwara Hirotsugu (藤原広嗣)

wounded Genbō to death" (Hirotsugu having died in a failed insurrection called the "Fujiwara no Hirotsugu Rebellion" after failing to remove his rival, the priest Genbō, from power).

Revenge of the onryō

Traditionally in Japan, onryō animated by the spirit of vengeance are believed to be capable of causing the death not only of their enemy, as in the case of Hirotsugu's spirit of vengeance held responsible for the death of the priest Genbō,

but also of causing natural disasters such as earthquakes, fires, storms, drought, famine, and pestilence as in the case of the spirit of the embittered Prince Sawara toward his brother, Emperor Kammu.

In common parlance, vengeance enacted by supernatural forces or beings is called tatari (祟り).

Emperor Kammu had accused his brother Sawara of plotting (possibly falsely in order to remove a rival to the throne), and the latter, exiled, had died from the consequences of a fast.

The reason the emperor moved the capital from Nagaoka-kyō to Kyoto was an attempt to avoid the wrath of his brother's spirit, according to a number of scholars. This was not entirely successful, and the emperor was forced to move the capital to Kyoto.

This was not entirely successful, so the emperor tried to lift the curse by appeasing his brother's ghost, performing Buddhist rites to mark his respect, and granting Prince Sawara the posthumous title of emperor.

A well-known example of appeasing the onryō spirit is the case of Sugawara no Michizane, who was politically disgraced and died in exile.

His vengeful spirit is then suspected of causing the deaths of his slanderers in quick succession as well as disasters (especially lightning damage), so the court attempts to appease the incensed spirit by restoring Michizane's former rank and position.

Michizane is deified in the Tenjin kami cult and Tenman-gū shrines are erected in his honor.

Examples of revenge onryō

Oiwa, from the Yotsuya Kaidan tale, is perhaps the most well-known onryō. In this story, the husband remains unharmed; however, he is the target of the onryō's revenge.

The vengeance exacted by Oiwa is not physical punishment but rather psychological torment.

Other famous examples include:

• How a Man's Wife Became a Vengeful Spirit and How Her Malignancy Was Hijacked by a Master of Divination. In this tale from the collection Konjaku Monogatarishū, an abandoned woman is found dead with all her hair and bones still attached. The husband, fearing reprisals from her spirit, asks a diviner (陰陽師, onmyōji) to help him. The husband has to grab her hair and ride her corpse. She complains about the heavy load and leaves the house to "fetch" (presumably the husband), but after a day she gives up and returns, after which the diviner is able to complete his exorcism with an incantation.
• On a broken promise. In this tale from Izumo province reported by Lafcadio Hearn, a samurai promises his dying wife never to remarry. He soon breaks the promise and the ghost first comes to warn him and then murders the young bride by tearing off her head. The guards who had been asleep chase the apparition with swords and while reciting a Buddhist prayer destroy it.

Onryō Physical appearance

Traditionally, onryō and other yūrei (ghosts) do not possess a particular appearance. However, with the increase in popularity of kabuki theater during the Edo period, a specific costume was created.

Extremely visual in nature and with a single actor often taking on different roles within a play, kabuki developed a visual shorthand system that instantly indicated which character was on stage as it emphasized the actor's emotions and expressions.

A ghost costume is composed of three main elements:

• white burial long kimono, 白装束 (shiroshōzoku) or 死に装束 (shinishōzoku) ;
• long uncombed black hair ;
• facial makeup consisting of a white background (oshiroi) combined with face paintings (kumadori) of blue shadows (藍隈, aiguma ), much as bandits are depicted in kabuki makeup art in addition to brown (代赭隈, taishaguma) and blue shadows or black kumadori (日本博学倶楽部 2005).