Solution for locale and character encoding issues in Japanese games on Steam Deck

The article explains two common issues when running Japanese games on Steam Deck: non-ASCII filenames not being accessible due to locale mismatches, and Japanese text displaying as mojibake or causing game crashes due to incorrect Windows ANSI codepage settings. It provides solutions for each problem, such as setting `LANG=en_US.utf8` in launch options for filename access and using `HOST_LC_ALL=ja_JP.UTF-8` for Japanese text support, but notes these fixes are mutually exclusive. The article then offers a workaround using a custom locale directory and `run.sh` script to enable both UTF-8 and Japanese Shift-JIS support simultaneously without requiring root access.

Problem 1 Cannot access filenames containing non-ASCII characters. Steam Deck's SteamOS 3 provides only one locale named en US.utf8 as configured in /etc/locale.gen but /etc/locale.conf sets LANG to en US.UTF-8 . They don't match, so the effective locale for programs is C and the character set becomes limited to ASCII. Set the game's launch options in Steam to LANG=en US.utf8 %command% to solve this. To fix this for all applications running in desktop mode eg. to correctly extract games , create a file named ~/.config/plasma-workspace/env/utf8.sh containing restart desktop mode to apply : sh /bin/sh export LANG=en US.utf8 Problem 2 Japanese text displays as mojibake or question marks. Some games may even completely fail to load due to script compilation errors common in visual novels . The Windows ANSI codepage must be set to SHIFT-JIS to fix this. Wine uses the current system locale set via LANG or the LC ALL environment variable to determine which ANSI codepage to use. This is equivalent to using Locale Emulator on Windows. Steam Deck's SteamOS 3 doesn't provide a ja JP.UTF-8 locale so this leaves LC ALL . However Steam may override it, so instead set the game's launch options to HOST LC ALL=ja JP.UTF-8 %command% to have Proton set LC ALL to the desired value. Problem 3 The simple solutions shown above to problem 1 and 2 are unfortunately mutually exclusive. ja JP.UTF-8 is not provided by SteamOS 3 so requesting it makes the effective Unix locale fallback to C ASCII again. Complete solution This sets the Wine codepage to Japanese and the Unix character set to UTF-8 without requiring root access or unlocking the readonly system partition of the Steam Deck. 1. Extract the archive steam-deck-jp-locale-utf8.tar.zst https://gist.github.com/cfillion/4394c3b8cd051fb45721187053e92296/raw/28178bed85fb027e99a4cfae431a36240f21acd8/steam-deck-jp-locale-utf8.tar.zst using Ark into the home directory on the Steam Deck /home/deck . 2. Double-check that /home/deck/locales/run.sh is executable right click properties permissions . 3. Set the game's launch options to LANG=ja JP.UTF-8 ~/locales/run.sh %command% to fix locale and encoding issues. Alternative steps Follow these steps instead to generate the files manually. A full install of Arch Linux is required commands may need adjustments to work in other distributions . 1. On an Arch Linux install: 1. Uncomment ja JP.UTF-8 in /etc/locale.gen 2. Run the following commands: sh sudo locale-gen mkdir locales export LOCPATH="$HOME/locales" localedef -f UTF-8 -i ja JP "$LOCPATH/ja JP.UTF-8" 2. Transfer the locales directory created above into /home/deck on your Steam Deck SteamOS 3 . 3. Create a file named run.sh inside that folder containing: sh /bin/bash https://gist.github.com/cfillion/4394c3b8cd051fb45721187053e92296 newlocpath=$ dirname "$ realpath "$0" " script=' BEGIN { FS=OFS=" '"'--'"' " } NF 1 { for i = 1; i < NF; ++i printf "%s", $i OFS; } { print "env LOCPATH='"'"'" newlocpath "'"'"' " $NF } ' command="$ awk -v newlocpath="$newlocpath" "$script" <<< "${@@Q}" " eval "$command" 4. Make run.sh executable: chmod +x ~/locales/run.sh 5. Set the game's launch options to LANG=ja JP.UTF-8 ~/locales/run.sh %command% to fix locale and encoding issues. Sources and tips - https://github.com/wine-mirror/wine/blob/120ca2ff52d145faa925a41d494035842d47a967/dlls/ntdll/unix/env.c L804-L805 - https://github.com/wine-mirror/wine/blob/120ca2ff52d145faa925a41d494035842d47a967/dlls/ntdll/unix/env.c L715-L719 - https://github.com/ValveSoftware/Proton/blob/4221d9ef07cc38209ff93dbbbca9473581a38255/proton L1081-L1087 - PROTON LOG=1 WINEDEBUG=+file,+nls,+msgbox %command% to troubleshoot file accesses, locales/character set conversions and message box contents.