Youkai

Yōkai (妖怪^?, ghost, phantom, strange apparition) are a class of supernatural monsters, spirits and demons in Japanese folklore. The word yōkai is made up of the kanji for "bewitching; attractive; calamity;" and "spectre; apparition; mystery; suspicious". They can also be called ayakashi (妖^?), mononoke (物の怪^?), or mamono (魔物^?). Yōkai range diversely from the malevolent to the mischievous, or occasionally bring good fortune to those who encounter them. Often they possess animal features (such as the Kappa, which is similar to a turtle, or the Tengu which has wings), other times they can appear mostly human, some look like inanimate objects and others have no discernible shape. Yōkai usually have a spiritual supernatural power, with shapeshifting being one of the most common. Yōkai that have the ability to shapeshift are called bakemono (化物)/ obake (お化け).

...
Wikipedia