What shapeshifting fox spirit appears in Japanese folklore?

The shapeshifting fox spirit in Japanese folklore is the kitsune.

Kitsune literally means “fox” in Japanese, but in traditional stories it becomes a fox spirit, or yōkai, endowed with intelligence and supernatural abilities. Kitsune may transform into humans, especially beautiful women, and use their disguises to deceive, test, help, or marry people. Many tales say a fox gains greater powers as it grows older and wiser.

Foxes are also associated with Inari, a major Shinto kami of rice, prosperity, and commerce. Inari’s foxes are often understood as messengers rather than the deity itself. This religious association helped give the fox both benevolent and mysterious qualities in Japanese culture.

Kitsune folklore includes kitsunebi, or fox-fire, and kitsunetsuki, the supposed possession of a person by a fox spirit. The tanuki is another Japanese shapeshifter, but it is a raccoon dog rather than a fox. Kappa are water-dwelling creatures, and tengu are winged or birdlike mountain beings, so none is the canonical answer here.