$ LANG=ja_JP.eucJP
$ export PYTHONUTF8=1
$ ./python.exe
Python 3.11.0a7+ (heads/main-dirty:29e2245ad5, Apr 27 2022, 17:57:13) [Clang 12.0.0 (clang-1200.0.32.29)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.stdin.encoding
'utf-8'
>>> sys.stdin.reconfigure(encoding="locale")
>>> sys.stdin.encoding
'eucJP'