According to japanese beliefs, the waira is a rare and reclusive yokai, of which very few have ever been encountered. It is an ugly beast with a large body similar to that of a cow, bearing a single sharp claw on each of its four long limbs. According to the few accounts that exist, males of the species are mottled in earthy brown colors, while females are red.

Waira live deep in the mountains, near heavily wooded temples and shrines. They are usually found near otoroshi, and are believed to guard temples and shrines in a similar manner. They uses their tough claws to dig up and catch small animals, such as moles, mice, and rabbits.

From the colorings and environments where they are found, it is believed that waira are transformed yokai, born from the common toad after it reaches an advanced age. It has also been speculated that the waira is closely related to the otoroshi, as they share the same habitat and are occasionally seen together.

The waira’s name, as with the otoroshi’s, is a subject of some confusion. However, the most commonly accepted theory is that it is a corruption of a variant of the word kowai, meaning "scary". This further supports the contention that the waira and the otoroshi may be somehow related.