MASAKUNI KAWASUMI II worked in the family bonsai business for decades, designing his own tools and cultivating bonsai on a professional level. He took over the business in 1950. Masakuni II is credited with popularizing bonsai around the world. For his work in tool making, he was awarded a Yellow Ribbon Medal by the Japanese Government in 1993. In 1996, he established the Masakuni Museum of Cutting Tools and Industrial Tools near Tokyo.
When his father died in 2002, MASAKUNI KAWASUMI III took over the business, which he runs today while continuing his research in the cultivation and care of bonsai.