im guessing your not that familiar with japanese gaming/culture. but they use english in a lot of games / advertisements/ everything these days. Its mandatory to learn basic english in school there for i think 6 years now.
But yeah, that is indeed a japanese Guitar Freaks, they just sing in english sometimes.
If you got a japanese PS2 which run about 170$, it would run all the GF games out right now which are 1-3 on PS1, 4thmix GF/DM combined game is on PS2. I hear theyre coming out with new mixes for PS2 soon and releasing a new controller sometime this year but there is no set date on this so dont hold your breath.
Almost all menus should be in english btw, on my PopN and IIDX games you dont need to know any japanese at all to use the game , song titles are in english.
edit: oh yeah, the PopN controller was 90$ for the dome buttons, i also have 2 normal buttons you cant see for start /select (although i found out that pressing both whites is the same as select so you dont need it). and a hacked PS controller and some wood/spray paint.
whole thing cost me like 120$ probably , sold as a rock. used 1/2 MDF