東京都交響楽団
is a Japanese conductor who has had an active international career since the 1970s. Koizumi was one among the founding conductors of the New Japan Philharmonic established in July 1972. He has appeared as a guest conductor throughout Europe and the United States, appearing with such ensembles as the Berlin Philharmonic and the Chicago Symphony Orchestra. He is the current principal conductor of both the Tokyo Metropolitan Symphony Orchestra, a post he has held since 2008, and the Century Orchestra Osaka (2003). Since 2006 he has been a current principal guest conductor with the Sendai Philharmonic Orchestra.