Is there such a place? I've been searching a lot, but can't find it. Most stores sells tablets from strange brands.
Google has a website that helps you find retailers: http://www.google.com/nexus/10/retailers/
Unfortunately, it doesn't look like any are listen in the Tokyo area. From what I've heard, Google controls the distribution of Nexus devices pretty tightly, so it's unlikely you'll find what you're looking for.