>yes, especially for cute/professional part of it it must be Japanese (maybe ハーフ girls in general, and foreign girls in gravure and JAV can be exceptions?)
"Japanese produced" is probably the guideline to follow - if it's a Japanese studio/group, then it's OK even if the subjects are non-Japanese

>It's a harder to say for amateur ero
I guess if it's clearly East Asian with no speaking (and would require significant research to determine whether it's Japanese or not), it can be left up

That said, regardless of origin/langauge, I don't think it's wise to allow genuine bullying/rape videos - especially when the age of the subjects is questionable