Onan Kainoa Satoshi Masaoka (born October 27, 1977, Hilo, Hawaii) was a Major League Baseball left-handed pitcher.
Drafted by the Los Angeles Dodgers in the 3rd round of the 1995 MLB amateur draft, Masaoka made his Major League Baseball debut with the Los Angeles Dodgers on April 5, 1999, and appeared in his final game on September 30, 2000.