1. You download nanami, and it's an iso that you burn on to a CDR.
2. Then you execute it on your PCE CD-based system.
3. Then to "back-up" a file, all that nanami does is display all the hex data of the save file on screen, and you have to manually write this down on a sheet of paper. (Though it's 10 billion times easier & much less error prone if you just to take a few snapshots via a digital camera.)
4. Then you run one of the nanami utilities on your PC, and once again, manually type in all that binary data back in. Obviously this is the part where it takes the longest time. (though quick for small save files, a long RPG game, you can be typing for a good 7-10 minutes).
5. This recreates the save file on your PC
6. Then you create an iso file using one of the tools included in nanami.A
7. Now you burn another CDR of this iso image.
8. Now with this CDR again, you have to option to write that save file back on to the PCE SRAM, or go back to step 3) whenever you want to "backup" another file.
In sum, the big cons of this system is that you have to waste a CDR every time you want to write the save files you have on your PC back on to your Duo, and step 4), since it's a pain-in-the-ass. But the big Pro is the fact that you have a permanent save file much more secure than a ten-no-koe bank, and you can store virtually unlimited number of save files on to that one CD. Once again, I only recommend that you "backup" files via nanami only after you know for a fact that the particular save file you want to save is the "final" version you want to archive. I basically treat ten-no-koe as my "temporary" backup these days.