Kadoban

Professional go handicaps were a system developed in Japan, in the Edo period, for handicapping professional players of the game of go against each other. With the abolition of the Oteai system, which from the 1920s had used some handicap games to determine the go ranking of professional players, this system has become obsolete. It is now completely superseded by the use of komidashi. Knowledge of it is required to understand the conditions of play in historical go matches, particularly the jubango that died out around 1960.
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When an "Ozeki" loses more than half of his matches. He must win a majority of his matches at the next tournament, otherwise he will lose his rank and be demoted.