Yokai are a broad class of supernatural beings, spirits, and phenomena in Japanese folklore, encompassing a wide variety of forms ranging from mischievous or dangerous creatures to protective household or nature spirits. While many yokai are associated with causing mishaps or embodying fears of the unknown, some traditions hold that certain spirits could ward off misfortune or guard specific places, though this varies greatly by region and legend. Their portrayal is not tied to a single doctrine but reflects centuries of oral storytelling, regional belief, and cultural imagination across Japan.