I once met a Chinese girl who was somewhat suspiciously fond of the English slang term (that I hadn’t heard of) “Jap’s Eye” which apparently means “urethral opening” and tbf I would never use the latter term either…

OTOH I had heard the term from time to time and it always came across to me (not Japanese - important caveat) as a pretty mild one, like “frog” for the French. I would be very unsurprised if it were different in the USA though, where there was such a big impact from WW2 and internment.