Koto (江東区, Kōtō-ku, "East of River") is a special ward located in Tokyo Metropolis, Japan. The ward refers to itself as Kōtō City in English.As of May 1, 2015, the ward has an estimated population of 488,632 and a population density of 12,170 persons per km². The total area is 40.16 km².Kōtō is located east of the Tokyo metropolitan center, bounded by the Sumida-gawa to the west and the Arakawa River to the east.