What really threw me was the absolutely impenetrable MOBA style games that seemed to fill entire levels on their own. They looked like they were designed for lots of long term play and grinding, and needed some kind of way to store progress. Even though I must have seen 50 of these machines filling entire floors at the few arcades I went to, I never actually saw anybody playing them.
There was however a dedicated "scene" in the basement of one of the arcades where they were playing some kind of competitive mech game. The cabinet was unusual in that it had arcade style controls, but also looked like it had a playstation-like controller as well (maybe as an option?)
I have no idea what the arcade culture or scene is like in Japan, but going in I thought I'd spend more time there and have more fun trying out weird stuff that hadn't made it to the U.S. In the end I think I found a Tekken 5 cabinet and played a few rounds against a few players and then left.