Yonashiro was born in São Paulo, Brazil on November 28, 1950. He joined Japan Soccer League Division 2 club Yomiuri in 1972. The club was promoted to Division 1 in 1978. In 1979, the club won first title JSL Cup. The club won the league champions in 1983 and 1984. The club also won 1984 Emperor's Cup and 1985 JSL Cup. He retired in 1986. He played 239 games and scored 93 goals in the league. He was selected Best Eleven 5 times.