It would be nice if you could add CDN nodes in Japan. Singpore is closer to us here than the U.S. west coast, but still not very close (typically 60 ms. RTT vs. 160 ms. RTT).
Japan may be particularly sensitive to what we consider high RTTs (>15 ms excluding the local loop) because 100 Mbps fiber local loops have been widespread since the mid-2000s and for the past several years virtually all new installs (home and business) are gigabit fiber. So when connecting to servers in Japan, everybody is used to sub-10 ms RTTs even on old Internet connections. Moving a server to Singapore multiplies that by almost an order of magnitude.