Restart your computer, extract the file, then change it back. Method C: Use Bandizip or WinRAR (Alternative)
Use the -mcp switch with Code Page 932 (Japanese) to extract: 7z x "YourFile.7z" -mcp=932 Japanese.7z
Version 19 and later have improved handling of Japanese half-width kana, reducing the occurrence of garbled text. Restart your computer, extract the file, then change it back
Alternatively, for a specific output directory: 7za.exe x -mcp=932 "YourFile.7z" -o"OutputFolder" Method B: Change System Locale (Windows) Restart your computer