Hi, first of all, thanks for reading this post, i'm not an hacker or an expert, just an hobbyst and all the analysis i have done in this thread are just my supposition, without any warranty or pretention to be true. I want to thanks MrCheeze for passing me the extdata dumping tool who allowed to dump the data First thing i have done, was to create a "Test" Mii, that you can scan with this QRCode: It's a complete default Mii, i only changed it's Birthday to be on the 01/01 because the field was blank previusly. Then, I dumped the extdata and I opened them using an hexeditor. The relevant part is here: Code: T<bh:00>e<bh:00>s<bh:00>t<bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00><bh:00>@@<bh:00><bh:00>!<bh:01><bh:02>hD<bh:18>&4F<bh:14><bh:81><bh:12><bh:17>h <bh:00><bh:00>)<bh:00>RHPJ<bh:00>h<bh:00>y<bh:00>r<bh:00>a<bh:00>c<bh:00>h<bh:00>y It does not look so good, so take some screenshoots: In my understanding, the Mii has 3 fields First one is the Mii's Name, 10 characters long, 20 bytes Second one are the Mii's data, 26 characters long Third one is the creator's name,10 characters long, 20 bytes (i cutted out extra empty spaces) Now let's look at the 3ds Mii creator customization possibility, I found them HERE These are a lot of options, especially because they are stuffed in 26 characters and half of them looks empty too! Sadly, i have no idea how to handle this kind of data, I hope that these information could be usefull for someone smarter then me. I'll do more test, especially working changing some variables and looking how it modify the data, but i'm not too optimistic. Anyway, thanks for reading and sorry for my bad English!