I don't think riju's tool works on a n3ds emunand, but you can do this :
- Backup your emunand with emunand tool
- Format your emunand with the gw menu (backup your sd card content first)
- Download the 9.0.0-20J or 9.2.0-20J (depending on your current firmware)
- Remove all the cias starting with 0004001B, 0004800F, 00048005, 00040130 and 00040138.
- Copy the 9.X folder in your micro sd card
- Boot into gw mod, use BBM to install all the cia from the 9.X folder, then do a format system memory
while in emunand (check if you see the GW3D first)
- Now download this pack :
http://jheberg.net/captcha/emunand-toolkit/
- Extract your emunand with emunand tool and put it in the emunand toolkit folder
- Put your nand xorpad in the emunand toolkit folder too.
- Execute decrypt_n3ds.bat
- Open WinImage then drag and drop the emuNAND.fat16.bin file on it.
- Go to the rw/sys folder, delete the SecureInfo_A (or B) and replace it with a jap SecureInfo_A (rename it SecureInfo_B if needed)
- Save and close WinImage.
- Execute reencrypt_n3ds.bat.
- Inject your emunand with emunand tool
- Boot into your emunand : it should be in japanese now.
- To remove the duplicated icons, delete all theses titles with FBI :
You need to extract it from a japenese 3ds... or just get one from that iso site, but it's like having a public header for the whole console.