User with this ability either is or can transform into an Tengu (lit. "heavenly dog", see Tiangou), with highly variable in appearance: some are almost completely bird-like with only minor humanoid features (this might include clothes), others are completely human, most are somewhere between these extremes. They are associated with the ascetic practice known as Shugendō, and they are usually depicted in the distinctive garb of its followers, the yamabushi.