Nijubango

Nijubango is a Japanese go term meaning twenty-game match.

This is a partial list.

Year	Players	Result(W-D-L)	Notes
c. 1671-c. 1675	Honinbo Doetsu, Yasui Sanchi II	2(?)-?-1(?)	There may be more than 20-games in the match. However, only partial game records up to game 20 exist. Honinbo Doetsu is known to have won at least two of the games and Yasui Sanchi II at least one.
1851	Honinbo Shusaku, Sekiyama Sendayu	13-0-7	Honinbo Shusaku won. Honinbo Shusaku held White the entire match.
1876-7	Honinbo Shuei, Kobayashi Tetsujiro	12-2-4	Kobayashi Tetsujiro was beaten down to Sen-ai-sen after game nine and to Josen after game 18. Matched ended after game 18.
1894-?	Tamura Yasuhisa, Tsuchiya Shugen,	?-?-?

Two 21-game matches were played with one between Hattori Intetsu and Yamamoto Genkichi in 1801 (nearly all games played over a single month) and another between Kadono Matsunosuke (Jowa) and Nagasaka Inosuke in 1807-8.