Mononoke

Statements on this practice can be found in detail in works like The Pillow Book and The Diary of Lady Murasaki.

However, this kind of thought still wasn't very influential at that time, and even Emperor Saga stated in a caution, "in this society, some would attribute any and all mononoke to a spirit's curse.

[6] Afterwards, in the Shoku Nihon Kōki, the author, Harusumi no Yoshitada, reflecting knowledge of onmyōdō, strongly adopted the concept of mononoke.

Just at that time, after Sugawara no Michizane died in Engi 3 (903), the deaths one after another that followed of members of the imperial and noble families, as well as the spread of epidemic diseases, were feared as the work of a curse of Michizane, and thus the belief that mononoke were caused by vengeful spirits' curses grew even stronger.

[6] Furthermore, due to the concept of the fear of "mono", the things that were said to be the origin of the illnesses, the ikiryō and shiryō themselves, were also thought to have been called mononoke.