Seiji Hirao (平尾誠二, 21 January 1963 – 20 October 2016) was a Japanese rugby union footballer and coach.

He played as a fly-half, and was one of the most popular Japanese players of his time, earning the name of "Mr. Rugby".

Hirao first played rugby at Fushimi Kogyo, in Kyoto, who won the national high school title in 1980.

Returning to Japan in 1986, he helped Kobelco Steelers to win seven consecutive National Championships, from 1989 to 1995.

He was the coach of Japan, from 1997 to 2000, and led his National Team at the 1999 Rugby World Cup.