No not all Japanese imports use the Japanese language.... quite a few of them are in English and some are mixed Jap/English and then of course you do get some that are entirely in Japanese!
I mainly get Japanese fighters such as Vampire Hunter, KOF, Fatal Fury, Darkstalkers, Xmen Children of the Atom etc.... and these are all in English, The only Jap import game i have that is all Japanese is Saturn Bomberman but i have screenshots on my pc for the English menu's
@alexh.... I have not come across any cartridges for the Saturn apart from the action replay , ram cart and memory cart for saves but there maybe others? I have a cartridge for the PS1 that stops the CD so it can be swapped, it plugs into the parallel port and also has cheats on it.