[1] Masui retired in 1997 and held the position of Professor Emeritus at the University of Toronto.
[citation needed] While still studying at Kyoto University, he taught biology, first as a teacher's assistant and then as a teacher, at Konan University, where he was promoted to assistant professor after his earning his Ph.D.
[citation needed] Masui died on April 18, 2024, at the age of 93.
[4] In 1998, Masui won the Albert Lasker Award for Basic Medical Research with Lee Hartwell and Paul Nurse for their pioneering work on cell division.
[5] He was elected a Fellow of the Royal Society (FRS) in 1998[6] and an officer of the Order of Canada in 2003 in recognition of his life's work.