User blog comment:Naty Ranmaru Sawada/Inazuma Eleven GO Galaxy Supernova/Big Bang Recruitments/@comment-24529314-20140330152218/@comment-24754440-20140330155245

I think you've got to clear the game once for the left route to unlock, not sure though since I didn't check that route out until I had beaten the game.

Also I think you get the Gold key somewhere on the Lost Galaxy planet (the last one which you unlock after clearing the game). Not so sure where the Silver one was again, but it's probably on one of the earlier planets.