新日本フィルハーモニー交響楽団
Born in Kyoto, Koizumi is a graduate of the Tokyo University of the Arts and the Berlin University of the Arts. In 1973, he was awarded first prize at the Herbert von Karajan International Conducting Competition in Berlin. From 1983–1988 he was music director of the Winnipeg Symphony Orchestra. He then served as the music director of the New Japan Philharmonic for many years.