Is Tau Chinese or Japanese?

I'm curious to know, could you clarify for me whether Tau is a character or term that originates from the Chinese language or the Japanese language? It's a bit of a mystery to me, and I'd appreciate your insight on this matter. Is there a clear distinction in terms of its etymology, or is it perhaps a term that has been adopted and adapted by both cultures in some way? I'm eager to learn more about the origins of this term.