Luiz Onmura began his love for judo at a local dojo in Vila Sônia in São Paulo before representing Brazil at international competitions for the best part of a decade. Onmura had his first success at the 1979 Pan American Games when he won silver in the featherweight class. The following year he won gold at the Pan American Judo Championships in Venezuela and competed at the Moskva Olympics. He won another silver at the 1983 Pan American Games, followed by bronze at the 1984 Los Angeles Olympics. In 1987 Onmura won his third and final silver at the Pan American Games, with him competing at his final Olympics the following summer in Seoul. His brother Nelson also won silver in the featherweight class at the 1987 Pan American Games. In 2016 Onmura had the honour of being one of the torch bearers ahead of the Rio Olympics.