I've mostly seen Japanese specifically called out on ad sites like bedpage rather than at any of the Asian agency sites (though VERY occasionally I will visit and find out the girl is Japanese). He is one example for you but I make no recommendation and would expect fake pics.

The only one I've found advertised as Japanese is Hosi, but she goes by different names. She isn't Japanese. She was raised in Japan, but not Japanee. She is also bat shit crazy so there is that, too.

On the same site who "claims" to be Japanese.

https://nova.bedpage.com/TherapeuticMassage/tanya-in-town-571-443-7383-if-you-wanna-know-what-is-onsen-japanese-massage-style/9661953.html