Japan has a long, long history of tiny restaurants and food carts. Most areas in Tokyo have many times more [0] restaurants than worldwide cities, just for this reason. There might be 20 small 8-seat ramen places in the same alleyway, whereas in other cities you'd have 2 or 3 larger restaurants spread out further.

[0] http://www.worldcitiescultureforum.com/data/number-of-restau...