Artwork by Kawanabe Kyōsai 河鍋暁斎 (1831-1889) 

Yōkai (妖怪, "ghost"; "phantom"; "strange apparition") are a class of supernatural monsters, spirits, and demons in Japanese folklore. 

Yōkai range diversely from the malevolent to the mischievous, or occasionally bring good fortune to those who encounter them. 

Artwork by Utagawa Kuniyoshi 歌川 國芳 (1844)