first you have to format your flash memory using the PS3 system, after that plug the flash memory to your computer open it and find update or system update folder, it could be a sub folder, then copy the update file which you download it before (the file has PUP extension ) to this folder and plug the flash m. to the ps3 system then goto system/ update , it something like that, I hope I helped you
for the update, I have a us ps3 version so I have to update it by using the us website or the us version, I don't know much about the jap version
this is the link to the us version update,:
http://www.us.playstation.com/ps3/network/updates
..."