Koichi Kubo (久保晃一, Kubo Koichi) (born Saitama, 13 January 1976) is a Japanese rugby union player with 20 international caps and 15 points in aggregate. He played as flanker and as number 8.

Kubo started his rugby career in high school, playing for Yorii High School team until his graduation in 1994, when he joined the Daito Bunka University team until 1998, when he graduated to play for Yamaha Júbilo, where he would play for his professional career until his retirement in 2009.^[1] In 2001, Kubo was appointed as captain of Yamaha Júbilo. Kubo also played in the Kansai representative team.

Kubo was first capped for the Japan national team on 11 November 2000, during the test match against Ireland, at Lansdowne Road. He also was called up in the Japanese roster for the Rugby World Cup 2003 in Australia,^[2] playing two matches in the tournament. His last international cap was on 4 July 2004, during the test match against Italy, in Tokyo.^[3]

Kubo is a great fan of Southern All Stars.^[4]