Last updated: 20210509
Step 1:
Download and run https://github.com/dezem/SAK
Step 2:
Select “NSZ to NSP”
Step 3:
Set the original NSZ files to unlock read-only.
Select “Open NSZ” and find/select the .NSZ file for converting. It takes about 3 minutes per 1GB of conversion. So if your game is 10GB, it will take up to 30 minutes.
PS: You will not see any progress bar, just “please wait” flashing. That’s normal.
Step 4:
Once complete, your will find your .NSP converted files in the SAME FOLDER where “SAK.exe” is at. Strange.. but that’s that.
Now install your game using the converted .NSP file.