Tatsumi (辰巳) is an area of Koto, Tokyo, Japan. It is surrounded by water on all sides, but is joined by bridges to Shiomi to the north, Shin-Kiba and Yumenoshima to the east, and Shinonome to the west. The west side is largely residential, the east largely consists of parks. It is built on reclaimed land. Its postal code is 135-0053.