[Dr. Yokai] Inoue Enryo's Scientific Theory of Yokai [Yokai Encyclopedia]

 What is Inoue Enryo?

Enryo Inoue was a Buddhist philosopher and educator. He was a teacher who focused on philosophy to gain diverse perspectives and built a school called Tetugakukan (means Philosophy Hall), which is now Toyo University.

He studied youkai (ghosts) in an attempt to break through the monstrosities and youkai and gave lectures on them, and was also known as "Dr. Haunted" or "Dr. Youkai".
He also developed a board game called "Tetugakutobisyougo" (meaning "Philosophy Flying Shogi"), a compromise of the rules of both Go and Shogi because it takes a long time to settle the game.

 Inoue Enryo (March 18, 1858 - June 6, 1919)

strangely classified

Inoue Enryo divided youkai into two main categories.
It is "Kyokai" and "Jikai".
He further explained that it can be subdivided into four categories: "Gikai" and "Gokai" within Kyokai, and "Kakai" and "Shinkai" within Jikkai.

Kyokai（虚怪）

A kyokai is not a youkai, but is assumed to be made from human fictions or errors in thinking.

Gikai（疑怪）

Gikai is a category of kyokai, and refers to man-made phenomena and youkai that are artificially caused by humans. They are also called artificial youkai, and are created for greed or other reasons.
Examples: Ghosts in haunted houses, ghosts in movies and plays, scarecrows in liver tests, etc.

Gokai（誤怪）

Gokai is another category included in Gikai, and refers to the monstrosities and yokai that are created by human error. It is also called an accidental youkai, and its true identity has been mistaken for something else, such as fear, as in the phrase, "I see the ghost's true identity, and it is a withered flower.
Example: A stone Jizo seen in the dark night is mistaken for a demon. Sounds of rain and wind sound like human voices, etc.

Jikai（実怪）

Jikai is the counterpart of Kyokai. In contrast to Kyakai, which are monsters and youkai that are created by human thought and misunderstanding and do not actually exist, Jikai are monsters and youkai that have been proven to exist.
Jikai is subdivided into two categories: "Kakai" and "Sinkai.

Kakai（仮怪）

Kakai is a category of jikai that refers to natural phenomena and other scientifically provable kaiju or youkai. They are also divided into two categories: Bukkai (physical yokai) and shinkai (psychological yokai).
Bukkai (physical yokai) are numerous and can be proven in various fields of physics, science, astronomy, geology, zoology, botany, etc. They are monstrous and youkai.
Example: Foxfire, Shiranui, mirage, etc.

There are many Shinkai (psychological yokai), and they include not only those that appear externally to a person, but also those that appear internally, such as dreams and possession.

Examples: strange dreams, fox possession, prophecy, etc.

Shinkai（真怪）

Shinkai is a category of youkai that is included in jikai and cannot be categorized into the above categories of kaiyos and yokai. It is a supra-rational youkai, which defines all things in the universe that are not youkai, such as water, pebbles, fire, etc., as being all youkai.

Summary

・Most of the monsters and ghosts can be scientifically proven.

・However, those that cannot be proven are recognized as "Shinkai".