The castle games (御城碁, oshirogo) were a series of important annual games played in the Shogun's castle by the best Japanese players of the day between the years on 1626-1863. The games were surrounded by the politics of the four main go houses (Honinbo, Hayashi, Inoue and Yasui) and three minor houses (Sakaguchi, Hattori and Mizutani), among other characters.
Only the following players were allowed to participate:
- heads of the four houses,
- their heirs, and
- 7 dan or higher players of other houses.
The castle games were played in the Shogun's castle by the best Japanese players of the day. The first castle game was in 1626. In 1664, the castle games became annual (with a few gaps). 1667 is the first year when more than one game was played. Starting from 1669, the castle games became exhibitions -- games were actually played elsewhere beforehand, and only replayed in the castle.
The last castle games were held in 1861. In the last years of the Tokugawa Shogunate, the political turmoil ultimately leading to the Meiji Restoration disrupted many Japanese traditional ceremonies and institutions -- and Go was no exception. -- 1862 exhibition games became the last of the long tradition.
In 1951, the games were compiled into a series of ten books, Oshiro gofu.
Pok: The article at gobase.org is based on my translation of an essay by Masukawa Koichi. I have revised this translation and published it under the title The Castle Games of the Edo Period - An Eye-Witness Report.