I've been to that watch store in Nakano. I was there four years ago for vacation. I bought a mint gen Speedy Pro for 2200 and my wife bought a five digit Sub for 4800. Prices have probably gone up since then.
From memory, there's also a pretty good selection at the Edion Akiba store. Same as the Osaka store.
Lots of grand Grand Seikos, and other beautiful timepieces.