The 2008–09 Top League was the sixth season of Japan's domestic rugby union competition, the Top League. The Toshiba Brave Lupus defeated Sanyo Wild Knights by 17–6 in the final of the Microsoft Cup to claim the 2008–09 Top League championship. The Top League is a semi-professional competition which is at the top of the national league system in Japan, with promotion and relegation between the next level down.