This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Yokai (Japanese)
Yokai are a class of supernatural entities and spirits in Japanese folklore. The word Yokai is composed of two kanji characters which both mean "suspicious, doubtful" and while it may be regarded as a loanword from the Chinese term yaoguai, the word Yokai has taken on multiple different meanings peculiar in Japanese context.
Yokai often have animal like features (such as the kappa, depicted as appearing similar to a turtle, and the tengu, commonly depicted with wings), but may also appear humanoid in appearance, such as the kuchisake-onna. Some Yokai resemble inanimate objects (such as the tsukumogami), while others have no discernible shape.