Studied under designers Choei Hara and Shigemitsu Hara. Established Koizumi Studio in 1990. In 2003, he opened Koizumi Tool Store as a place to convey his designs. He has designed everything found in daily life, from architecture to chopstick rests. At present, he is traveling across Japan to visit manufacturing sites and continue his collaboration with local communities. In 2015, he launched the general incorporated association Wazawaza and began working to restore handcrafts. Professor Emeritus at Musashino Art University. Winner of the Mainichi Design Award in 2012 and Grand Prize of the Japan Crafts Exhibition in 2015.