He joined Japan Soccer League Division 2 club Yomiuri in 1972.

In January 1985, Yonashiro was approved for naturalisation as a Japanese citizen by the Ministry of Justice.

[1] In October, when he was 34 years old, he was selected to the Japan national team for the 1986 World Cup qualification.

In September 1994, he became a manager for Kyoto Purple Sanga as Seishiro Shimatani successor.

In June 1996, he became a manager for Kyoto Purple Sanga again as Oscar successor.

This biographical article related to a Japanese association football midfielder born in the 1950s is a stub.