Jidayu Koizumi (å°Âæ³Â次大夫, 1539 - 1624 January 27) was the Secretary of Water and Hatamoto magistrate of the early Edo period.
Koizumi was responsible for creating the Rokugo and Nikaryo canals along the Tama River in order to irrigate surrounding farmland.
Other engineering projects created by Koizumi can be found in Jidayubori park along the Nogawa River.