Chinese and Koreans do think Japanese are ugly.
Because Japanese have shorter legs than their bodies, while Chinese and Korean have longer legs than their bodies. And the Japanese don't like hard food, which makes their teeth ugly.
The ancient name of the Japanese was "倭", which was given to them by the China. "倭" is a combination of two letters. The letter on the left means people, and the letter on the right means short, so "倭" means short and short legged people.
This is one of the most important national treasures of Japan. It was given to the Japanese by the emperor of the Han Dynasty when he conferred the title of King of Japan in 200 BC. The above text is the gold seal of the king of "倭":
View attachment 864700
Japanese teeth:
View attachment 864702
View attachment 864703
Japanese star's legs:
View attachment 864704
Korean star's legs:
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Ordinary Chinese legs:
View attachment 864706
That may be true but we need to behave in civilised ways in public.
A Japanese person reading that they are "ugly" would find this kind of remark offensive like anyone else would.
Personally I find East Asian women very attractive, be they Chinese, Korean or Japanese. Makes no difference to me.
Thank you for educating me a little more on the physical differences in your region.