Add ~/.dub/bin to your PATH if needed.
sudo apt install dub
Step 1: Launch MKVToolNix GUI Open the program after installation. shinseki no ko to o tomari dakara dub install
Step 2: Add Source Files
Step 3: Configure Tracks
Step 4: Set Default Flag
Step 5: Start Muxing
Result: You now have a new file that has the "Dub Installed." When you open this new file, it will play in English. Add ~/