This is way too late of an answer but since i was looking for Cheats for Danganronpa S as well and didn't find anything until messing around with stuff myself i figured i should post it in one of these threads so that other people can find it. It's stupidly simple.
1. You have to backup your Danganronpa S Save, i did it with JKSV. I just named mine "cheat"
2. On your PC, go inside the backup folder, so in my case JKSV/Danganronpa S Ultimate Summer Camp/cheat
3. There'll be a file named "DraSaveData.dat". Open that in any text application, i literally just used the normal Notepad
4. Near the top there is a line "Monokuma:???\nGoldMonokuma:???\nMonomi:???" The question marks are just the amount of coins you have. Now you can simply input any number of coins you want into each of the 3 fields. so maybe like this "Monokuma:9999\nGoldMonokuma:9999\nMonomi:9999" After you've done this, save your changes.
5. Back on the switch you just have to restore this save again with JKSV or whatever. Then open the game and you'll have the amount of coins you specified.
I hope this helps anyone, i was searching the net for a while before i just tried editing the save file myself. As much as i like the idea of the game, the low amount of coins you can reasonably grind is pathetic.