Seiji Hirao (平尾誠二, born Kyoto, 21 January 1963) was a Japanese rugby union footballer and is a current coach. He played as a fly-half. He was one of the most popular Japanese players of his time, earning the name of "Mr. Rugby".
Hirao first played at Fushimi Kogyo, in Kyoto, who won the national high school title, in 1980. He then moved to Doshisha University, where he won three national universities title. He graduated in 1985, moving to England, where he played a year for Richmond. Returning to Japan in 1986, he helped Kobe Steel Kobelco Steelers to win 7 consecutive National Championships, from 1989/90 to 1994/95.
He had 35 caps for Japan, from 1982 to 1995, scoring 1 try, 5 conversions and 1 penalty, 18 points in aggregate. His first match was a 22-6 loss to New Zealand Universities national team, at 30 May 1982, aged only 19 years old. Hirao played at the 1987 Rugby World Cup, all the three matches. He also played at the 1991 Rugby World Cup, as the captain, again in all the three matches, and, after a three years and a half retirement, at the 1995 Rugby World Cup, playing two matches and scoring a try in the 50-28 loss to Ireland, at 31 May 1995. That would be his last cap for his National Team, aged 32 years old.
He was the coach of Japan, from 1997 to 2000, and lead his National Team at the 1999 Rugby World Cup. Japan was unfortunate, losing all the three matches but giving worthy performances.