How many Mii data files are in AKB48+Me? I've heard that there's over 400, but I want an exact number. Also, why would they need so many Miis in the first place?
Since I didn't end up getting many questions for the anniversary post, I'll reply here.
AKB48+Me, the Japan-only 3DS game, does contain over 400 Mii data files. Few games (like Wii Party) do something different with their Miis, which is combine every Mii data file into one larger file, instead of having every Mii data file separate in a folder or archive container file. AKB48+Me does something similar, but instead of combining all Mii data files into one larger file, it combines them into multiple larger files.
For example, in the game’s \romfs\miidata\ folder, you can find 6 .bin files, each with “MiiStoreData” at the beginning of their filename. All six of these MiiStoreData files contain a different amount of Miis. While I haven’t had the time to fully extract all these Miis, and please forgive me for replying with incomplete information, but it seems most of these Miis are unique.
MiiStoreData.bin contains 66 Mii data files, MiiStoreData_old.bin contains 8, MiiStoreDataDefaultPlayer.bin contains 3 (likely the three female Guest Miis, though I can not readily confirm this), MiiStoreDatakennkyuusei.bin contains 100, MiiStoreDataMob.bin contains 46, and MiiStoreDataSkins.bin contains 66.
This alone results in 289 Mii data files in one folder spread across 6 larger files - however, this is not the only place Mii data files are stored. The game’s \romfs\common\mii_data\ folder contains 5 more larger Mii container files, with the only one missing from the previous folder being the MiiStoreDataDefaultPlayer.bin file.
In this other folder, MiiStoreData.bin contains 66 Mii data files, MiiStoreData_old.bin contains 8, MiiStoreDatakennkyuusei.bin contains 100, MiiStoreDataMob.bin contains 23, and MiiStoreDataSkins.bin contains 66.
In this folder alone, that adds up to 263. Adding both folders results in the total number of Mii data files in the entire game: 552. Running a byte comparison check between the folders, it seems only MiiStoreData_old.bin is the exact same between both folders - the other 4 files are at least somewhat different from each other. Additionally, when comparing the Mii data files individually, MiiStoreDataMob.bin is the only one with any similarities, with 23 Mii data files being exactly identical. This doesn’t mean the other files can’t share identical Mii data files, as the order could just be changed, but that would require extensive extracting.
So in total, 552 Mii data files, with 521 of them being completely unique (as I know of so far). I hope this is a good enough answer for now until I completely extract them. Thank you for the question.

















