Kamaitachi.

Kamaitachi (鎌鼬, かまいたち) is most famously imagined as a weasel-like yōkai that rides dust devils or cold whirlwinds and cuts flesh with sickle-shaped claws. Regional descriptions vary. Some portray it as an invisible slicing wind, some as a spiny-furred beast with a dog's cry, and some as a trio of linked entities whose attack follows a fixed pattern. The creature is therefore both an animal and a phenomenon.

That ambiguity is central. Kamaitachi is what happens when the wound seems real but the attacker never fully comes into view. It is folklore's answer to sudden laceration in a world of snow, dry wind, and unexplained pain.

Kamaitachi attacks are known for a distinct sequence. A person stumbles or feels struck by a gust; only afterward does a deep cut appear, often with little pain or immediate bleeding. In some famous Shinano and Hida versions, three beings work together: one knocks the victim down, the second slices the flesh, and the third applies medicine so the injury does not kill. That paradox, brutal wound without ordinary aftermath, makes the legend especially memorable.

Other regions reinterpret the phenomenon through mantis ghosts, cursed sickles, blood-sucking winds, or funeral tools left too long in fields. The name remains stable, but the explanatory frame shifts with local climate and custom.