I found this in a blog:
In Japanese folklore, the nine tailed fox takes on the appearance of a beautiful woman. Tamamo no mae (藻の前), which in English means, “The Beautiful Fox Witch” is a story about the nine tailed fox’s disguise as a woman. The emperor happens to fall in love with the woman, but the more he falls in love, the sicker he becomes. There’s a term in Japanese called kitsunegao (キツネ顔), which means “fox-faced”. Generally speaking, the Japanese view women with “fox faced” features as attractive. These “fox faced” features refer to women who have a small, oval face and prominent cheekbones; which are supposedly features like those of a fox.
Perhaps that’s where the Tamamo no mae story originated from, but like Tamamo no mae, the transformation of the nine tailed fox as a woman is a metaphor for falling and the pain that occurs to the lover (usually in reference to men) when involved in such a love.
I didn't think anyone would use it as a metaphor now
