Therefore, many full-time foreign professionals from Southern Hemisphere countries played in the Top League, notably Tony Brown, George Gregan and Dan Carter.

NTT Shining Arcs and Yamaha Jubilo which won their 2005 promotion/relegation play-offs (Irekaesen) against Canon Eagles and Kyuden Voltex to retain their places for the 2011–12 season.

Additionally, in the Wildcard play-offs, the Top League teams ranked 5th and 8th (Kintetsu Liners and Yamaha Jubilo) played each other at Hanazono, Osaka, as did the teams ranked 6th and 7th (Kobe Steelers and Ricoh Black Rams), with the winners (Kobe and Yamaha) also qualifying for the All-Japan Rugby Football Championship.

Honda Heat and Kyuden Voltex were automatically relegated at the completion of the 2009–10 season for finishing 13th and 14th.

Toyota Industries Shuttles and NTT Communications Shining Arcs won promotion through the Top Challenge series.

IBM Big Blue and Yokogawa Atlastars were automatically relegated at the completion of the 2008–9 season for finishing 13th and 14th.

Kyuden and Sanix retained their places in Top League when they won their respective promotion and relegation play-offs.

Secom and World (13th and 14th) were automatically relegated, to be replaced by Kyuden Voltex, the third team from Kyushu to enter the league, and Mitsubishi Sagamihara DynaBoars from Kanto.

After the pre-season 2005 Challenge series, Secom and Sanix returned after a year out of the league, replacing Kintetsu and IBM.

Following the 2004 Challenge series with IBM and Toyota being promoted, the following 12 teams competed in the second season: Toshiba won both the league round-robin and the Microsoft Cup knockout competition contested by the top 8 teams after the regular season.

The eleventh and twelfth teams (Kintetsu and IBM) were automatically relegated, and the ninth and tenth placed teams (World and Ricoh) had to win their 2005 promotion and relegation play-offs (Irekaesen) to stay in the Top League, which they did.