| Countries: |  Japan |
| Date: | October 2005 – February 2006 |
| Champions: | Toshiba Brave Lupus |
| Runnersup: | Sanyo Wild Knights |
| Prevseason: | 2004–05 |
| Nextseason: | 2006–07 |
The 2005–06 Top League was the third season of Japan's domestic rugby union competition, the Top League.[1]
Toshiba Brave Lupus won both the league round-robin and the Microsoft Cup knockout competitions.
| Team | Region |
|---|---|
| Fukuoka Sanix Blues | Fukuoka, Kyushu |
| Kobelco Steelers | Hyogo, Kansai |
| Kubota Spears | Chiba, Kanto |
| NEC Green Rockets | Chiba, Kanto |
| Ricoh Black Rams | Tokyo, Kanto |
| Sanyo Wild Knights | Gunma, Kanto |
| Secom Rugguts | |
| Suntory Sungoliath | Tokyo, Kanto |
| Toshiba Brave Lupus | Tokyo, Kanto |
| Toyota Verblitz | Aichi, Tokai |
| World Fighting Bull | Kobe, Kansai |
| Yamaha Jubilo | Shizuoka, Tokai |
| Top League Table | ||||||||||||||
| Club | Played | Won | Drawn | Lost | Points For | Points Against | Points Difference | Try Bonus | Losing Bonus | Points | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Toshiba Brave Lupus | 11 | 9 | 0 | 2 | 406 | 193 | 213 | 10 | 0 | 46 | |||
| 2 | Sanyo Wild Knights | 11 | 9 | 0 | 2 | 416 | 276 | 140 | 6 | 0 | 42 | |||
| 3 | NEC Green Rockets | 11 | 9 | 0 | 2 | 270 | 136 | 134 | 4 | 1 | 41 | |||
| 4 | Toyota Verblitz | 11 | 7 | 0 | 4 | 431 | 263 | 168 | 6 | 3 | 37 | |||
| 5 | Kobelco Steelers | 11 | 7 | 0 | 4 | 284 | 225 | 59 | 4 | 1 | 33 | |||
| 6 | Suntory Sungoliath | 11 | 6 | 0 | 5 | 308 | 241 | 67 | 6 | 2 | 32 | |||
| 7 | Yamaha Jubilo | 11 | 5 | 0 | 6 | 328 | 211 | 117 | 4 | 4 | 28 | |||
| 8 | Kubota Spears | 11 | 4 | 1 | 6 | 324 | 297 | 27 | 5 | 0 | 23 | |||
| 9 | World Fighting Bull | 11 | 5 | 1 | 5 | 166 | 200 | -34 | 0 | 1 | 23 | |||
| 10 | Secom Rugguts | 11 | 2 | 0 | 9 | 260 | 481 | -221 | 6 | 1 | 15 | |||
| 11 | Ricoh Black Rams | 11 | 2 | 0 | 9 | 137 | 398 | -261 | 2 | 0 | 10 | |||
| 12 | Fukuoka Sanix Blues | 11 | 0 | 0 | 11 | 134 | 543 | -409 | 1 | 1 | 2 | |||
| The top 8 teams qualified for the Microsoft Cup play-offs. The top 4 teams also qualified for entry into the All-Japan Rugby Football Championship. | ||||||||||||||
| [2] Four points for a win, two for a draw, one bonus point for four tries or more (BP1) and one bonus point for losing by seven or less (BP2). | ||||||||||||||
The top eight teams in the league played off for the Microsoft Cup (2006) knock out tournament, which was won by Toshiba Brave Lupus.
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See main article: 2006 Top League Challenge Series.
Coca-Cola West Red Sparks and IBM Big Blue won promotion to the 2006–07 Top League via the 2006 Top League Challenge Series, while Honda Heat, Kintetsu Liners, Kyuden Voltex and NTT Communications Shining Arcs progressed to the promotion play-offs.
Four promotion/relegation matches (Irekaesen) were played, with the winner of each qualifying for the 2006–07 Top League. The 9th, 10th, and 11th placed team from the Top League played against the 3rd, 2nd, and 1st placed teams, respectively, from Challenge 2. The 12th placed team from the Top League played against the 3rd placed team from Challenge 1. --------------------So Fukuoka, Ricoh, Secom, and World all remained in the Top League for 2006–07.