As far as I remember since last year I think Japan only have Junior and Master division, I remember people in Japan e-mailed asking the pokemon company why they decide to take out Senior division and I think they never replied or something like that. I know for Worlds they do had Senior division as seen this past Worlds, but we never find out how they were gonna do the qualifiers and etc without Senior Division in Japan since Tsunami canceled all the events and I believe if I'm not mistaken in Japan they still play without a Senior division till today, unless Japan decide to change that again this year with the upcoming qualifiers.
But overall, yeah Japan is playing HS-on, and BW-on was the Battle Carnival's format which it was a fun event.