Capsized Checksum Fixer
How to use:
1) Run the fixer and open your modified STFS container. A message should inform you that the fixer was successful.
2) Rehash & Resign the container with Horizon or your preferred program.
I will eventually create a save editor later.
Have fun ;)
Be careful to modify your secrets, the game has a glitch, which makes the achievement unachievable!