The Nihon Ki-in (日本棋院), also known as the Japan Go Association, is the main organizational body for Go in Japan, overseeing Japan's professional system and issuing diplomas for amateur dan rankings. It is based in Tokyo. The other major Go association in Japan is Kansai Ki-in. Its innovations include the Oteai system of promotion, time limits in professional games, and the introduction of issuing diplomas to strong amateur players, to affirm their ranks.
The Nihon Ki-in was established in July 1924. The first president of the Nihon Ki-in was Makino Nobuaki, a great Go patron himself, with Okura Kishichiro serving as vice president. The vast majority of pros at the time joined the fledgling organization, excepting the Inoue faction in Osaka and Nozawa Chikucho. A brief splinter group called Kiseisha was created soon after the Nihon Ki-in was formed, but most of the players involved had returned to the Nihon Ki-in within a couple of years.
The Nihon Ki-in organizes many tournaments for professional players. The major title tournaments include the Kisei, Meijin, Honinbo, Judan, Tengen, Gosei, and the Oza. There are also separate Honinbo, Meijin, and Kisei titles for women.