Yo-kai

are a folk of supernatural beings that are invisible to humans and one of the main focuses of the Yo-kai Watch series.

Overview
Yo-kai are spiritual beings whose influence is responsible for every one of the strange, paranormal events in the human world. Most of these influences range for example, from sudden changes in the behavior of people or abnormal weather in otherwise normal days, as well as unexpected landscape changes or control over a different force of nature.

With some exceptions, most Yo-kai are invisible to humans without the Yo-kai Watch. In some cases, some Yo-kai can disguise as humans by putting a magical leaf on their heads, such as seen by Komasan and Komajiro in the anime, or by more conventional forms of shape-shifting, such as Kyubi. Also in the anime, some Yo-kai are made permanently visible due to the circumstances of their death, such as Manjimutt.

Most of them being based on the Yo-kai from the traditional Japanese folklore, most Yo-kai have unusual body compositions, such as being single-eyed or multi-eyed, or even multi-armed; others may be based on inanimate objects (which are known under a umbrella sub-category of Yo-kai known as ) or even food; ranging from being based on animals like mammals, birds fish or insects; and even more traditional demons or creatures from Japanese folklore.

Several Yo-kai used to be humans (such as Manjimutt or Hungramps), animals (such as Nechigaeru or Jibanyan), or even inanimate objects (such as Wazzat or Sakasakkasa). Though the process for becoming a Yo-kai is largely unknown, most Yo-kai develop an attachment to an important place of their previous lives, with several having "unsettled business" to fulfill; however, doing so does not make them pass to the other side.

Though most Yo-kai, being technically ghosts, cannot "die" in the strict sense of the word, they can have their souls (kon) forcefully removed, leaving an empty shell behind. The "death" can be reversed by returning their souls, however. Those who can die simply have a supernaturally long life span.

It is not yet clear when were the first Yo-kai came into existence, though several of them were around since the Sengoku Period. Some Yo-kai, known as the Classic Yo-kai, can be found until at least 60 years prior the start of the series, along with other Yo-kai which can also be found in the present, with others being encountered only in this time period. Likewise, Merican Yo-kai can be found in St. Peanutsburg, U.S.A., implying that other areas of the world have their own individuals of Yo-kai, not just Japan.

Tribes of Yo-kai
Originally, every kind of Yo-kai are divided into the eight main tribes/classes;, , , , , , and Slippery (Nyororon). In the video games, each of the tribes their own strengths and rariety, and if two or more Yo-kai of the same tribe are adjacent to each other, they will recieve a Tribe Unity bonus. In Yo-kai Watch 2, is introduced, consisting of the Kaima Executives and the Kai. In Yo-kai Watch 3, will debut as the 10th main class with Android Yamada being the first from class to be revealed so far.

Present Yo-kai

 * Yo-kai which are found in the present. The ones with normal are silver, while others who have  or U Medals are both green.

Classic Yo-kai

 * Yo-kai introduced in Yo-kai Watch 2: Bony Spirits and Fleshy Souls wholly based on youkai of classic Japanese mythology. They are only found in the past. Their medals are the, which are identified as red with traditional Japanese drawings, the two corners are squared and their names are writing traditional Japanese writing font and are found in different positions than other Yo-kai Medals.

Merican Yo-kai

 * Yo-kai to be introduced in Yo-kai Watch 3: Sushi and Tempura. As the name implies, they are from America. They are considered a subgroup of Present day Yo-kai. Their medals are the Merican Medals. Like Classic Medals, these medals are red, but are vibrant with comic book aesthetics and their names are written in word bubbles.

Legendary Yo-kai

 * : A group of powerful Yo-kai  that can only be befriended after filling out Legend Pages in the Yo-kai Medallium, which is done by collecting certain sets of Yo-kai Medals to break the seal surrounding a pacific Legendary Yo-kai, with each seal requiring a different set of 8 required Yo-kai. Like many species of Yo-kai, a Legendary Yo-kai falls under one of the tribes. Their Yo-kai Medals are identified by the color gold.

Merican Legendary Yo-kai

 * : A group of Legendary Yo-kai from America, much like Merican Yo-kai, to be introduced in Yo-kai Watch 3.

Great Legendary Yo-kai

 * : A special group of Legendary Yo-kai in Yo-kai Watch 3, who were originally famous people before their death.

List of Yo-kai in the Yo-kai Medallium

 * List of Yo-kai by Medallium Number (Yo-kai Watch)
 * List of Yo-kai by Medallium Number (Yo-kai Watch 2)