明治学院大学
After returning to Japan, he was involved in the protest movement against the compulsory fingerprinting of foreign residents in the early 1980s. He lectured at Meiji Gakuin University and International Christian University in Tokyo, before being appointed to the University of Tokyo. In 2013 he retired from the University of Tokyo to take up the position of University Professor at Seigakuin University in Saitama Prefecture, near Tokyo.