Toshi Kasai is a Japanense record producer, engineer, mixer and musician. He is most well known for his strong vocal production work with hard rock and metal groups such as his long standing relationship with The Melvins and his work with Tool. In addition to his recorded production work, Toshi was a member of the band Big Business and Nate Mendel's band Lieutenant. He is also a member of Altamont, The Dale Crover Band. In 2019, he opened for Melvins and Redd Kross under his own name, playing Moog Synthesizer to oscilloscope and projections.