1x157 - Urusei Yatsura

Inspired by a movie about a fox using a spell to turn a human girl he loves into a fox like himself for one night, Kitsune looks for Shinobu to find his missing gingko nuts, which he wants her to eat under a full moon to do the same. Ataru and Lum help them. Kitsune eventually finds them, turning Lum, Ataru, Cherry, Shinobu, AND Kotatsu-Neko all into foxes, as well as many of the people in town partially into foxes as well. A half-fox Shinbou and Kitsune dance together under the full moon, happy together.