Sorry, replying to this string a bit after the fact:
I've been living in and diving in Japan for 12 years - I started diving after getting here.
I've gone from OW to 2Star Instructor [CMAS], with a lot of diving - fun and work-related - in Japan or with Japanese tourists when I was travelling in Asia-Pacific or where ever.
I'm very fluent in Japanese, have permanent residency here, and my wife is Japanese, so I clearly don't have a racist bone in my body. Really, I don't!!! :->
As a result, I read all the previous posts on this topic with interest.
I have found Japanese to be both very risk-adverse and very groupist - as a result, one finds them in closer groups, close to the guide, and behind the curve when it comes to developments that _might_ [or should! :->] be considered risky, like nitrox, tech, cave, deco, etc.
Risk-adverse means a greater use of guides and greater dependence on the guide than I've found diving in other Asian countries or Canada. Perhaps this is why AA found some shops offered shorter dives, the thinking being "why dive to the dive table's margins?"
To be clear, I've never experience a shop that preferred a 40 minute dive for the reasons AA explained. I'm just suggesting another take on the subject.
When you have a group in which the members are gathered too closely together, coral gets bumped or stepped on, heads get bumped with tanks, masks get finned off, and so on.
That I _have_ experienced/observed [I had my mask finned off in Palau when diving with a large group of Japanese...] when diving as a tourist.
As a result, I've found it best to get off the boat first to put a bit of space between myself and the group and hang a bit off to either side, or enter last, again hanging off to either side. Entering with the group is not the best thing.
So I share AA's frustration with a bad dive experience.
I've also found a generation gap - a lot of the ol'timers still set up their gear like it was 20,30 years ago, with gauges dangling, cigarettes in their mouths until putting on their fins on the transom/beach, and a little less ecoawareness than is currently the norm.
Conversely, I've found younger divers to be "on par" with current norms.
Concerning commercial supply of air, I think I prefer knowing that the person filling my tanks passed a standardized set exam in order to pump what is going into my body.
Finally, as an instructor and while guiding, I feel I've helped my clients, of any nationality, to learn good eco-friendly dive practices, and I hope that when I'm travelling as a tourist, my hopefully ecofriendly actions speak louder than words.
Cheers,
Jonathan