I once got interviewed by a Japanese company (Mitsubishi Heavy Industries). My impression is that business atire is extremely conservative. Generally they don't wear anything fancy that would stand out (like fancy cufflinks, pink shirts). Likewise, it's all short simple hair styles (possibly the only interview I've ever been to that discussed my hair style...). The trends towards flexible work atire that you see in the US and Europe I don't think has really taken hold in Japan. Business-casual is right out.
One interesting difference in Japan is that in factory environments, on the factory floor white collar workers are expected to wear the same blue overalls as line workers(with the overalls worn over the suit shirt and tie,
like this). Generally, Japanese companies are quite keen on group solidarity within a company, rather then the executive/manager/worker split you might see in American companies.
If you're sticking out, or the clothes are tight and showing off your body, you won't do well in Japan. I'd say even a gold watch would be frowned upon. Not really the kind of environment for any self expression, at least where clothing is concerned.