ROM Hack Transferring save from JPN to US game

[Haryor]

Hey!
As you may know, although the Switch is region-free, games have different published versions, such as Japanese and American ones.

I've played Sushi Strikers, Dragon Quest Builders and Hyrule Warriors in their Japanese versions, and would like to use them with their American-published cartridges I currently have.

First of all, has anyone tried if the saved games are automatically compatible between regions? And, if not, would anyone have a guess about the viability/ease of hex-editing those saves from JPN edition games for use with their US published versions?

Thanks!

 

[FAST6191]

Not tested anything but the general trend carries whether you are doing an 8 bit puzzle game or a modern bells and whistles RPG, give or take the Switch having a container format for its saves as opposed to raw whatever the dev cooked up. Container is not bad if the dev leant into it for verification; most saves have a checksum, usually quite custom and over an unknown segment (though you can usually make a good guess), and that tends to be the big obstacle in save conversion.

Generally not that much changes between regions in terms of general approach. The trouble tends to come in the absolute changes. Custom names for characters is usually the first main hurdle as Japanese will usually use its own 16 bit encoding where outside it then it might drop to 8 bit, or at least not support the Japanese stuff.
If this also carries with it a change in data stored then everything after each text segment will be shuffled how much more or less is given over to that. This is where it starts to get fun.
If it gets really fun then the order of things will be shuffled around.

All this can add up to many hours of work even if you know what you are doing here (possibly even if you are given a guide on what to do, though that tends to be less), which with basic cheats you might be able to get back to the same point in the game in a fraction of. You might also be able to force imprint the stats from one save to the other as well; if the save writes down stats/custom names each time (and it is easier to dump a whole set of player data rather than grabbing bits piecemeal, especially on modern stuff where you are not so limited by save chip size) then you can figure out what your base save is/was and recreate that in cheat form (stats/names tending to be the easiest but inventory is not out of the question either, just might take a few runs as you add in everything if you have limited cheat space and thousands of items).

 

[Otakyon]

Most of the time, for different region games you can simply swap the savefile using JKSV. I did it with some games, some may not work through, you have to try yourself.

Do the follow:
1) Make backup saves of your japanese games
2) Start a new game on your american games (you need to create the savefile first)
In some cases, the ID will be different for each region of the game. If this is the case:
3a) locate the american one and make a backup of your new save (give a different name between this and the japanese). Now, explore the SD card with a program of your choice. Locate the japanese save inside the JKSV directory, copy the folder of the save and paste it next the the american folder . Now back to JKSV program, and press restore on the japanese save.
3b) if the ID is the same between region, you will find your japanese save already ready to restore in JKSV.