Probably not the answer you're looking for but I also haven't watched every single historic feudal Japan anime so I can not definitely say for certain it doesn't exist.
Authors and script writers write for a modern audience who understand best a modern, living language. So it's rather unlikely that the majority of a work be entirely or heavily in ...
Animes That are set in the Most far distant future.
Ergo proxy is the only anime that is set in the most far distant future. The story takes place in year 7207 where earth takes a thousand years to recover from a Global environmental disaster
Ergo Proxy: Year set in 7207
-GUNNM: 26 century
-Land of the lustrous: (Unspecified) The anime is set in a Far, ...