yeah, not tested yet but looks it work +/- like DX/melee but without language selection :B
If we are able to find the files separately and switch/replace the English one to the japanese, would work fine
I don't really know how the stuffs works inside the game... for example I dont know if possible to replaces Ft mark to Meters like the original(and all the rest of the world xD), or something like replacing the englsh on US version to the Portuguese of EUR version, and stuffs :B