Right first of all, "they play with a lot of structure", thus fundamentally removing themselves from resembling the "traditional Japanese style of play".
Second of all, wehther by "little midfield carrying" you mean the individual midfielders themselves or the team as a whole trucking it up in midfield? Fact is they revolve a lot more around controlling the pace than they do around width, it's not as if they are chucking it out to the wingers and hoping.
Just because they have structure doesn't mean they don't play to their traditional strengths which was techincally adept backs with a lot of pace having a go form pretty much everywhere. For example Tatekawa doesn't kick the ball defensively once in all three test matches.
They control the pace of the game by doing exactly that, they sling it wide and try and create 1 on 1's or 2 vs 1 in the back line and move opposition teams defensive alignment around at pace - but they don't do that through midfield punch groups.
They are quite happy surrendering possession if it is the outcome of their outside backs getting a chance against their opposition wingers.
So actually they do sling it wide and hope to get a scoring chance, their desire to keep it alive sees them play high risk rugby that brings great trys but also frequently sees them shipping points.
That's my opinion, you don't have to agree.
Back on the topic of teams stylistically. I still don't get where your idea of teams having to conform to "indigenous" styles comes from. With different coaches we have seen teams tactically be remarkably different. Wales under various different coaches would be a good example, compare Gyppo era Wales to Gatland era Wales. The best coaches though will, as Feicarsinn said, be able to tailor gameplans towards the players they have at their disposal.
A: I never said a team had to conform to an indigenous style. I sid most teams do, and that scotland have suffered from abandoning theirs.
B: Of course tactics change but a teams style of play will generally revolve around traditional strengths - Indigenous = traditional or the natural/native game played.
England 2002, best attacking side in the world at the time, but still steeped in their traditional strengths.
People seem to think that Wales were 15 slight ducking and weaving players all through the 70's, when in fact the bulk of the team was solid and they had a couple of flashy players at 9&10 and in the back 3, much like today.
The traditional welsh style of play is very much physical confrontation. Get on the front foot and then keep that foot on the throat - that's why they've always struggled against SA and NZ as they had packs that could stand up and backs as physical as the welsh. When they lost that physicality (late 80's early 90's) they struggled against teams like Samoa and Fiji who could match them physically.
