It would be VERY difficult to get to the front if you entered later. It might not be completely impossible, but you would probably make a lot of people very angry in the process if you managed to find a way up.
So this is Zepp Tokyo, where the finale was filmed (not too far from DiverCity). I don't think DiverCity had the middle divider, and there may have been some openings in the rows -- I can't really remember. But this should give you a general idea anyway.
http://www.japantimes.co.jp/wp-conte...Zepp-Tokyo.jpg