|Title Matches Played|
|March through April|
|Time Allotted (Title)|
|Time Allotted (League)|
The Juudan tournament is a Japanese professional go competition featuring a challenge against the Juudan for his title.
Until 2011, players competed in a a 16-player league tournament for the right to challenge the Juudan.
Preliminaries were held by the Nihon Ki-in:
- The B/C preliminaries:
- 26 players from the Tokyo branch
- 10 players from the Kansai and Chubu branches (combined)
- The A preliminary:
- 13 players from the Tokyo branch
- 5 players from the Kansai and Chubu branches (combined)
- The final preliminaries:
- 8 players from the A preliminary
- 14 players seeded from last year's tournament
The Juudan used a double-knockout system. Under this system, a player who lost a game in the league tournament was knocked down to a parallel losers' tournament. The winner of the main tournament and the winner of the parallel losers' tournament played to determine who had the right to challenge the Juudan.
The winner of the series gains (or retains) the title of Juudan.
The top eight players were seeded in the league for the next year's Juudan tournament.
In 2012, the format of the Juudan changed significantly. As of 2012, the Juudan is a 20-player league single-knockout tournament. The two semifinalists are seeded in next year's tournament.
"Juudan" may be assumed as an honourary title by players who have won the title 10 times in a row, or at the age of 60 or at retirement by players who have mounted 5 successful sequential defences of the title.
It takes 22 months to progress from Preliminary C to the final title match.
- Preliminary C
- July through September (first year)
- Preliminary B
- October through December (first year)
- Preliminary A
- January through March (second year)
- Last Preliminary
- April through June (second year)
- Main Tournament
- July (second year) through February (third year)
- Title Matches
- March through April (third year)
|January||A Preliminary||Main Tournament|
|February||A Preliminary||Main Tournament|
|March||A Preliminary||Title Matches|
|April||Last Preliminary||Title Matches|
|July||C Preliminary||Main Tournament|
|August||C Preliminary||Main Tournament|
|September||C Preliminary||Main Tournament|
|October||B Preliminary||Main Tournament|
|November||B Preliminary||Main Tournament|
|December||B Preliminary||Main Tournament|