The most dreaded type of yūrei is the onryō. They are the ghosts of people who died with such strong passions jealousy, rage, or hatred that their soul is unable to pass on, and instead transforms into a powerful wrathful spirit who seeks vengeance on any and everything it encounters. Onryō appear as they did when they died. Often they were victims of war, catastrophe, betrayal, murder, or suicide, and they usually display wounds or marks indicative of the way they died.
Their motive is always the same: vengeance. Onryō are easily powerful enough to swiftly kill any person; however, they prefer letting the object of their hatred live a long life of torment and suffering, watching those he knows suffer and die. They inflict a terrible curse on the people or places that they haunt. This curse can be transmitted to others through contact like a contagious disease, creating a circle of death or destruction that is far more devastating than any ordinary ghost. They make no distinction in whom they target with their grudge; they just wants to destroy. Moreover, this vengeance can never be satisfied as it can for most ghosts. While most yūrei only haunt a person or place until they are exorcised or placated, an onryō’s horrible grudge-curse continues to infect a location long after the ghost itself has been laid to rest.
Occasionally, an onryō’s curse is born not out of hatred and retribution, but out of intense, passionate love which perverts into extreme jealousy. These onryō haunt their former lovers, exacting their wrath onto new romances, second marriages, their children, and eventual end up destroying the lives of the ones they loved so much in life. Whatever the origin, the onryō’s undiscriminating wrath makes it one of the most feared supernatural entities in all of Japan.
Unquestionably the most well-known onryō, and one whose grudge-curse exists to this very day, is the ghost of Oiwa: a young woman who was brutally disfigured and then murdered by her wicked and greedy husband in an elaborate plot. Her story is told in Yotsuya Kaidan, The Ghost Story of Yotsuya, and has been retold many times, in books, ukiyo-e, kabuki, and film. Like with Shakespeare’s Macbeth, legend has it that a curse accompanies her story, and that those who retell it will suffer injuries and even death. To this day, producers, actors, and their crews continue to visit the grave of Oiwa in Tokyo before productions or adaptations of Yotsuya Kaidan, praying for her soul and asking for her blessing to tell her story once again.