Yokai are mystical creatures, spirits, or monsters that reside in the Yokai Realm. Yokai are supernatural entities an can include a wide variety of different species and sub groups.
Classification of Yokai
KamiKami are yokai that are gods, spirits, or deities. These yokai can often shift between our reality and the Spirit Realm and can be some of the most powerful mystic beings in the world. They are often immortal, though sometimes they're corporeal form tethering them to the real world can be destroyed. Sometimes kami are just malicious ghouls or lost spirits taken physical form. Kami often follow their own set of rules, but ultimately are all bound to the spirit realm in one way or another.
BakemonoBakemono are monsters and beasts. They are different than kami, as they are born and alive in the physical world, and are not bound to the spirit realm. They are living beings that can all get hurt, sick, and even die. These make up a significant portion of the yokai population, including oni, tengu, kappa, shapeshifters, animal folk, kitsune, jorogumo, etc. These creatures each of their own biology and culture, but will frequently coexist together in big cities. You can often find certain species of bakemono gathering in small tribes or villages when leaving the bigger cities.
TsukumogamiTsukumogami are objects that of been possessed by a spirit, or come to life on their own. This can happen with objects that have been enchanted with magic, or naturally through 100 years of use. These objects can develop their own personality and mystic abilities, occasionally becoming powerful artifacts. Often the only way to destroy a tsukumogami that has gotten out of hand is to purge the spirit from the object and then destroy it.
HengeHenge was word used to describe shapeshifters, but now can include anything that was human and takes a monster form, or was a beast that takes human form, even if that creature was not born a yokai. This means, in a way, Mutants can be considered henge.
Civilization and Culture
Average Technological Level
Most areas in the yokai realm tend to be pretty far behind technologically compared to the human world. This is because mystic magic plays a significant role in their daily life, and that doesn't tend to breed innovation. They often avoid brining in human technology from the human world as it's considered taboo and dangerous. Though in many ways, their magic system mimic human technology, such as a power grid ran by crystals that behaves much like a human world electrical grid.
Culture and Cultural Heritage
Yokai involve a wide variety of creatures and spirits recognized by cultures all over the world, who each have their own interpretations of the strange creatures who sometimes leak from from their world. Yokai have adopted many human cultures from around the world, and homogenized them into their own mystic based culture, but in places like North Gekkou the culture most resembles Edo era Japanese culture, primarily with their fashion and architecture. If you move beyond the cities that are heavily influenced by their neighboring portals, you will find small villages and colonies of yokai with their own unique rules and customs of their own.
Yokai have existed for as long as humans have, if not longer, and have played a role in human's lives for centuries. They would travel back and forth between the yokai realm and the human world through portals that would appear naturally. The human world had resources that the yokai realm did not, and yokai would trade humans for mystic items. However, this would often prove to cause chaos in the human realm, often from malicious kami, or mystic magic gone awry. After a while, humans would deem yokai as dangerous demon that the needed banished from this world. Yokai would be killed or locked away in the yokai realm to keep humanity safe, but also restricting the yokai from valuable resources. The yokai would try to fight back, invading the human world during what would become the Yokai War. During this war, the most powerful Tsukumogami the world has ever seen, the Yoroi Ketsueki, was born. The yokai and humans would eventually form a truce in order to fight their new common enemy, and after the war had ended, they made a pact with 10 warrior clans from around the world known as the The Guardian Clans, who would protect the portals between the realms and trade resources with the yokai. Over the next several hundred years, these clans would begin to die out, resulting in radio silence from the human world in many parts of the yokai realm. This has caused quite a lot of restlessness among the yokai, many of whom have begun sneaking into the human world once more.
Interspecies Relations and Assumptions
Yokai have close ties with humans. While it's not uncommon for a yokai to enter the human world and fall in love with a human, if they're true identity is discovered, it makes things complicated and they will usually run away, never to be seen again. Offspring between humans and yokai are also common, but due to the mystical nature of these children, they are often considered under the umbrella of yokai.