Hon'inbō Shūsaku, Japanese Go player (born 1829)

Shusaku was a Japanese professional Go player during the 19th century. He is known for his undefeated streak of 19 games during the annual castle games; his thirty-game match with Ota Yuzo; the eponymous Shusaku opening; and his posthumous veneration as a "Go sage". Next to his teacher, Hon'inbō Shūwa, he is considered to have been the strongest player from 1847/8 to his death in 1862. He was nicknamed Invincible Shusaku because of his castle games performance.

Go is an abstract strategy board game for two players in which the aim is to fence off more territory than the opponent. The game was invented in China more than 2,500 years ago and is believed to be the oldest board game continuously played to the present day. A 2016 survey by the International Go Federation's 75 member nations found that there are over 46 million people worldwide who know how to play Go, and over 20 million current players, the majority of whom live in East Asia.