Tenryū was a city located in western Shizuoka Prefecture, Japan. Tenryū was founded on November 3, 1958. On April 1, 2005, the city had an estimated population of 22,643 and a density of 124.65 persons per km2. The total area was 181.65 km2. It is now part of Tenryū-ku when the city of Hamamatsu became a designated city on April 1, 2007.