I am deeply sorry for the loss of Professor GUO Yujun. She was my student with intelligence, diligence, and sense of humility when she was at Hokkaido University from October 1991 to April 1993. Although she returned to Wuhan after short stay in Japan, we were in contact with each other. I received her last e-mail in January 2023. I do not believe that she passed away only months later. 

OKUDA Yasuhiro

Professor emeritus at Chuo University (Tokyo) and Hokkaido University (Sapporo)