This tournament is the oldest in the world and in some ways the most prestigious - amateurs who are champions of their company, school, college or whatever still like to call themselves Honinbo.
In its early days it was unchallenged as the premier title. Today, though, to the hard-nosed pros it currently ranks only third on the money scale, but it is still a very rich tournament.
The winner's prize is 25 million yen and the runner-up gets a fifth of that. Game fees are generous, too. In the final league the winner of each games gets 800,000 yen and the loser 600,000 yen.
Just getting to one of the leagues is goal enough for many pros, and staying there guarantees a lucrative living - but demotion causes a painful shock.
The long-time sponsor is the newspaper Mainichi Shinbun. The event is open to all pros in the Nihon Ki-in and Kansai Ki-in. The format has changed over the years. Term 1 in particular was notorious for taking several years.
It was really several tournaments packed into one Pandora's box, and after all that a tie ensued so that the winner was declared to have won on points in previous games.
The early terms were also disrupted by the war, as was one famous match. One of the most famous games ever was the Atom Bomb game in Term 3 which was taking place in a suburb of Hiroshima on the day the bomb fell.
We will limit ourselves to describing the current format, but two changes are worth special mention. One is that komi changed from 4.5 to 5.5 points from Term 30 onwards (and was 0 points in the final of Term 1).
The other is that time limits have been drastically shortened. Even league games used to be two-day events. Now only the final spans two days.
The preliminaries begin with a partial knockout for players of 1-dan to 4-dan. This gives four Nihon Ki-in players and two from the Kansai Ki-in. They join all the senior players in a second-stage knockout in another partial knockout which gives 32 players. The four players demoted from the previous league are added to these. They all compete in what is called the Third Preliminary.
The players are divided into four groups of nine. In each case, two play off in Round 1 and the eight players left then play a normal knockout among themselves. The winners of these four knockouts take the four vacant places in the league.
The league has eight players. They all play each other once and the winner plays a best-of-seven title match with the holder from May to July. If there is a tie for first place in the league a play-off is held. In the case of ties in the demotion places, the higher ranked player (league ranking - column 1 in the table above, not dan ranking) retains his place. Where ranking is equal, play-offs are held.
Time limits are 5 hours each except in the final, where each players has 8 hours (was 9 hours until 1989).
The grave of Nikkai
The Honinbo (strictly Hon'inbo) title is the oldest in Japan. Originally it was the priestly name of a Buddhist monk Nikkai, from his abode in the Jakkoji temple in Kyoto, where he is buried.
He was later (1605) known as Honinbo Sansa and was appointed the first Meijin by the Shogun in 1612. The successive heads of the school he founded took the title of Honinbo until the 21st and last hereditary holder, Shusai, surrendered it to the Nihon Ki-in for an annual event.
A vestige of the traditions is retained in the custom of a new Honinbo taking a new name upon his accession. To give one example, Kato Masao became Honinbo Kensei while he was the holder and, to add gravitas, decided to use an old form of the character for Ken (sword).
In his case the name was an allusion to his nickname as the Assassin, but others may choose names that allude to teachers or people they admire. Perhaps because the Honinbo is so bound up with Japanese tradition, foreign-born winners have so far declined to adopt this custom, and since Cho Chikun (and later Cho Sonjin) have held the title for so long, the custom is in danger of dying out.