Tadashi Osanai (1910–1977) co-founded Korg and designed early rhythm machines that launched Japanese electronic percussion.

A Tokyo Imperial University engineering graduate and virtuoso accordionist, Osanai performed with a Wurlitzer Sideman rhythm machine and persuaded nightclub owner Tsutomu Kato to finance a better design. The DoncaMatic DA-20 (1963) resulted — Japan's first home-grown drum machine.

Osanai continued developing rhythm units and experimental synthesizer accordions at Keio, laying groundwork for the 1973 miniKORG and MS-series monosynths engineered by Fumio Mieda.

Notable products: DoncaMatic DA-20, Keio rhythm machines, Korg miniKORG.