I'm surprised you don't even know how to use jksm, anyway, I'm assuming you have jksm installed? I'll just assume yes, open it go to titles and look for ultra moon hit save and export the save. Transfer said save to a computer in a manner of your choice (ftp, taking out the SD card etc). Download pkhex, open pkhex, should say something about open on the top left find your save file, and click open. After this you will be able to see the contents of your save drag and drop the pk7 file into pkhex and the information should appear then right click on an empty space in ur box and hit set then on the top left again hit export main or something like that hit save it somewhere transfer back to 3ds in the folder where your original save back up was, open jksm and hit import and your done congrats bye.