What historical cultural use was made of *uguisu* droppings?

Answer

As a skin whitener and cleanser by geishas and kabuki actors

The droppings, known as *uguisu* powder, were historically utilized by geishas and kabuki actors as a skin whitener and cleanser, a practice which persists commercially today with sterilized guano.

What historical cultural use was made of *uguisu* droppings?
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