Well, ok, to be specific, Japan was a racist imperialist power circa WW2, as most people probably know. The fact that it was an empire and no longer is, but has a government that has often maintained a rose-colored view of the past, makes Old Japan a pretty obvious companion piece here for the other empire nostalgia-fascism. But on top of that, there is also the tendency among extremely online western right-wingers to assert that present-day Japan is based for (supposedly) being so much more right-wing than the degenerating leftist America/etc. So on top of the actual imperialist history, there is this appropriative component as well. Which feels relevant to me since Dirk grew up in America.
Actually, this summons a few other comparisons in my mind if you want to get really deep into it - 1) Dirk growing up in the ruins of an America (imperialist power) destroyed by Alternia (another imperialist power) vis a vis America's bombing and occupation of Japan as a strategic move in the upcoming cold war and 2) the shockingly obvious comparisons between Dirk and Yukio Mishima. But maybe that is for another thread.