Tetsu Yasui (安井てつ, March 24, 1870 – December 2, 1945) was a Japanese educator and writer.
[1] Her father was a weapons instructor to Doi Toshimoto, a daimyō of Koga Domain.
[2] From 1904 to 1907, she lived abroad in Bangkok, Thailand, where she served as the acting principal of the Rajini Girls School.
[2] When Tokyo Woman's Christian University was founded in 1918, Yasui was appointed as the first dean.
[4][5] She came out of retirement briefly in 1942 to become principal of the Toyo Eiwa Jogakuin, a girls' school founded by Canadian missionaries.