Yep, that must be them. They appear to be quite impressive. 400,000JPY in 1988 is uh, $7500 today. They resell for a lot more than that, I imagine. The NSX10Ks are not quite as insane as the 150KG GF-1s, which were seven million yen a pair in 1991 (~$110,000 today).
I actually do use all four. The other two are the fronts in my HT system. The odd man out is my 10-years-newer B&W CDN-CNT center channel speaker. It's funny looking, but it manages to hold its own sonically.