The Myōshōji River (妙正寺川, Myōshōji-gawa) is designated as a Class A river by the Japanese government with a length of 9.7 km and a basin area of 21.4 km².
Due to the progress of urbanization, the water retention capacity of the Myōshōji River has fallen and there is an increasing risk of water damage. To cope with this situation, the Tokyo Metropolitan Government has constructed revetments that can handle rainfall of up to 50 millimeters per hour.
