Sekiyama Sendaiu was one of the strongest amateur
Go players in the Edo period. When he was a pupil of the 10th
Honinbo, Retsugen, he received a shodan diploma.
In 1851 at the age of 67 he played a famous nijubango with
Honinbo Shusaku which he lost by 13-7.
Some years later, at the age of 71 he played a jubango with Shuho.
He lost this series with 8 - 1 and one jigo.
Sekiyama Sendaiu was of about 5 dan professional strength.