If you are using a standard console or non-restricted custom firmware (CFW), use the built-in system tools:

~600–800 MB (excluding updates).

If you enjoy the game, support The Gentlebros. The developers are a small team (two brothers) who actively released free DLC (The Cursed King) instead of charging for it. Pirating their work undermines future projects like Cat Quest III (announced for 2024–2025).