Yuurei are more commonly female than male, victims of male cruelty or neglect. Those who become Yuurei typically die violent deaths, whether by suicide or by murder; they become trapped on earth until they have taken care of unfinished business. Male Yuurei are less common, although a slain warrior may become one in order to set the record straight regarding the manner of his death, i.e. to clear his name from disgrace.

Although most Yuurei are relatively harmless, some may become “Obake-Yuurei,” or monster ghosts. Obake-Yuurei, instead of restricting their passions to reasonable limits, are wont to loose their rage and sorrow on any people who happen to be unlucky enough to pass by.