Shuetsu

Honinbo Shuetsu (本因坊 秀悦), a.k.a. Tsuchiya Shuetsu (土屋秀悦), (1850–1890) was the eldest son of Honinbo Shuwa. He became the fifteenth head of the Honinbo house after the death of Shuwa in 1873. He passed headship to his youngest brother Shugen in 1879 due to mental collapse and increasing ill health.

400 Years of Go in Japan says that he suffered from mental instability on account of the burden of being Honinbo during the low point of Japanese Go.