Gah, I hate J-pop/rock with a passion.
I only know a few metalheads here, and they're all into the underground death/grind scene, so I don't know if Opeth is popular. There's some great bands here which I think I rambled on about in another thread. Anyway, the only (relatively) big show I've gone to see is Napalm Death and Suffocation, and whilst it was a fucking great show, it was strange... the crowd would cheer really intensely for a few seconds, then all of a sudden it'd go dead quiet. You could literally hear someone coughing on the other side of the club.
Anyway, no Opeth in Japan for me cause:
1) I live nowhere near Tokyo (and don't want to

)
2) Japanese festivals are too expensive
3) I'll be back in Australia by then anyway.
Edit: ^^^^ Corrupted are fucking great. Finally getting to see them next month.