Utagawa Kuniyoshi in the context of "Woodblock print"

In mythology and folklore, a vengeful ghost or vengeful spirit is said to be the spirit of a dead person who returns from the afterlife to seek revenge for a cruel, unnatural or unjust death. In certain cultures where funeral and burial or cremation ceremonies are important, such vengeful spirits may also be considered as unhappy ghosts of individuals who have not been given a proper funeral.

In feudal Japan to early modern Japan (1185–1868), a rōnin (/ˈroʊnɪn/ ROH-nin; Japanese: 浪人, IPA: [ɾoːɲiɴ], 'drifter' or 'wandering man', lit. 'unrestrained or dissolute person') was a samurai who had no lord or master and in some cases, had also severed all links with his family or clan. A samurai became a rōnin upon the death of his master, or after the loss of his master's favor or legal privilege.

In modern Japanese, the term is usually used to describe a salaryman who is unemployed or a secondary school graduate who has not yet been admitted to university.