Steam Deck - Visual Novel Game

https://www.visualnovelwiki.org/en/general/jp-locale

Automatic Script for Steam Deck

cd Downloads
sh ./japanese_locale_enabler.sh
y

Lutris JP Locale

Flatpak

 

flatpak config  --system --set languages 'en;ja'
flatpak config  --user --set languages 'en;ja'
flatpak update