Nagasaka Inosuke was pupil of the Yasui school, first half of the nineteenth century. Officially rated 2 dan but considered of 6 dan strength. From June 1807 to June 1808, Nagasaka played a 21 game series against Todani Matsunosuke, the future Honinbo Jowa, winning 8 games and losing 13. At the time Jowa was a 4 dan. The series began with Nakasaka taking white in each game (josen). By the 13th game, Nagasaka having fallen behind in the series 4-8, the playing conditions were changed to Nagasaka playing white in two games out of three (sen-ai-sen). These conditions held for the remainder of the series.
Jono64a? What is wrong with this picture? Surely Jowa as the higher ranked player would have been giving a handicap, not Nagasaka. Then after he fell 4 games behind, the handicap would have been increased.