Today lets share a small tool for extract private header from original game card.
.3ds game backup from original game card
Step 1: Extract Gateway3DSHelper and open Gateway3DSHelper.exe
Step 2: Change the path to you roms, double click the original .3ds game
Step 3: Click export(导出) to get the private header, you will find .bin in the file, it is the private header for this game.
Use this Private header:
Step 4: Choose game you want to play online, click import(导入) to choose the .bin file you just made
Step 5: Change the unpaired information until them paired, Factory(芯片厂商), ROM size(ROM 大小), Unknown(未知), card type(卡带类型)
Tips: don’t change the cartridge ID,
factory option: C2 AE 45, choose the one your original card is.
ROM size: choose the size your game is
Unknown: most of this is 00
Card type: only 2 option, just change to another if it not pair
Step 6: Click apply(应用) to use this private header
Step 7： Last but important, don’t forget click Change the extension to .3dz(修改扩展名为.3dz), then online…
Tips: don’t play US ROMs online on JP 3DS, you can use EU 3DS play US roms