was a Japanese pianist who became devoted to American jazz very early in the wave of Japanese jazz enthusiasm. He became a member of the Cozy Quartet in 1956 after Toshiko Akiyoshi's departure, playing alongside Sadao Watanabe.[1] Robin Kelley, in his biography of Thelonious Monk, says that before his inaugural 1963 tour, "Monk's greatest champion in Japan was not a critic but a pianist named Yagi Masao. In 1959, the twenty-six-year-old pianist formed his own group featuring several Monk tunes in their repertoire, culminating in his debut LP, Masao Yagi Plays Thelonious Monk, recorded in the summer of 1960."[2] Later in the 1960s he played with Charlie Mariano, Hidehiko Matsumoto, and Helen Merrill, and in the 1970s led his own ensembles. He was well-known as a composer and arranger, and wrote copiously for film soundtracks.