I work in Chiyoda-ku (Marunouchi), but live in Minato-ku (Azabu).
I've been to Natural, but it must have been a bad day, since I thought their stuff didn't look all that nice and the staff wasn't very helpful. When I wanted to buy a pink chijimitosaka, they admitted that their specimens looked bad because they didn't give it enough light, but that some good light should bring it back to life. It's pretty hard to find chijimi in pink, so I bought this in wishful thinking despite the high price that they refused to bring down. (They seemed pretty confident that it would come back to life.) It mostly melted away to nothing, but it wasn't all for naught. It has grown back a bit and I now have a mini-pink chijimitosaka that is super healthy since it grew in my tank's conditions. I wasn't planning to go back though.
But if you consider it that nice, I am always willing to give it a second look. I live off the nanboku line, so it's pretty convenient to get to.