What is "sentetsu"

Yasui Sentetsu (安井仙哲, 1734–1780) was a Japanese Go player, who is said to be born in either Aizu or Kawachi Province. His year of birth is unknown, but his birthname is believed to be Hara Gonhei. He served as an apprentice to Yasui Shuntetsu Senkaku.

In 1748, he changed his birthname to his present name, and began playing castle game oshirogo . As he was part of a famous Go house, he would play with the other Go houses in the shogun's castle. In 1775, his mentor Yasui Shuntetsu Senkaku retired, causing him to become the sixth head of the Yasui house.

He died on September 4, 1780.