I bought an Edge E520.. I expected the BIOS language to be Japanese but it's in English, which is what I want.
I want to update the BIOS but I'm afraid the one from Japan Lenovo's site will change the language to Japanese.
Yes you can.
"The BIOS is usually written in the assembly language of the CPU used in that computer. An assembly language is a human-readable notation for the machine language for a specific processor; machine language (also called machine code) is a very basic programming language that provides instructions that can be read directly by a processor."
It is recommended that users download the ISO disc image and burn the image to a CD before booting from the CD to run the update.