Tetsurou

I'm not sure if it's just me, but is it really not possible to return to the Spinel Town area after completing Episode 15? I've checked Route 1 and the Underground Railnet, but the path to the mountain from Route 1 is gone and the gate in the Railnet is closed, even though the puzzle is complete. It's a slight source of distress for me, actually -- one of my main motivators for finishing everything after getting a Plume Fossil from the Circus was the possibility of extracting an Archeops... Well, if you do know, thanks in advance!