While all Japanese ghosts are called yurei, within that category there are several specific types of phantom, classified mainly by the manner they died or their reason for returning to Earth.
- Onryo – Vengeful ghosts who come back from purgatory for a wrong done to them during their lifetime.
- Ubume – A mother ghost who died in childbirth, or died leaving young children behind. This yurei returns to care for her children, often bringing them sweets.
- Goryo – Vengeful ghosts of the aristocratic class, especially those who were martyred.
- Funayurei – The ghosts of those who died at sea. These ghosts are sometimes depicted as scaly fish-like humanoids and some may even have a form similar to that of a mermaid or merman.
- Zashiki-warashi – The ghosts of children, often mischievous rather than dangerous.
- Samurai Ghosts – Veterans of the Genpei War who fell in battle. Warrior Ghosts almost exclusively appear in Noh Theater. Unlike most other yurei, these ghosts are usually shown with legs.
- Seductress Ghosts – The ghost of a woman or man who initiates a post-death love affair with a living human.
There are two types of ghosts specific to Buddhism, both being examples of unfullfilled earthly hungers being carried on after death. They are different from other classifications of yurei due to their wholly religious nature.
In Japanese folklore, not only the dead are able to manifest their reikon for a haunting. Living creatures possessed by extraordinary jealousy or rage can release their spirit as an ikiryo ???, a living ghost that can enact its will while still alive.
The most famous example of an ikiryo is Rokujo no Miyasundokoro, from the novel The Tale of Genji.
Yurei often fall under the general umbrella term of obake, derived from the verb bakeru, meaning “to change”; thus obake are preternatural beings who have undergone some sort of change, from the natural realm to the supernatural.
However, Kunio Yanagita, one of Japan’s earliest and foremost folklorists, made a clear distinction between yurei and obake in his seminal “Yokaidangi (Lectures on Monsters).” He claimed that yurei haunt a particular person, while obake haunt a particular place.
When looking at typical kaidan, this does not appear to be true. Yurei such as Okiku haunt a particular place -in Okiku’s case, the well where she died-, and continue to do so long after the person who killed them has died.