It is easy to forget while negotiating the subway map and strolling miles of concrete that Tokyo is at heart a river town. When the shogunate set up Edo, the area to the west of the castle was hilly, uptown Yamanote. To the east along the banks of the river Sumida-gawa lay the working class merchant downtown district, Shitamachi. Here is where the world-class Tsukiji fish market lives. Here is a part of that district where Tokyo life has been vibrant since the beginning.