Tatsuhiko Kawashima, the father of Japan's Crown Princess Kiko and a professor emeritus at Gakushuin University, died on Thursday, according to the Imperial Household Agency. He was 81.
His death followed the marriage of his granddaughter former princess Mako Komuro to her commoner boyfriend Kei Komuro on Oct. 26.
Kawashima was admitted to St. Luke's International Hospital in Tokyo on Oct. 19. The crown princess and her two daughters visited the hospital multiple times to see him, according to sources familiar with the matter.
The Tokyo native was also the grandfather of Prince Hisahito, 15, who is second in line to the Japanese imperial throne, and Princess Kako, 26.
Known for his frugal lifestyle, Kawashima, a professor of economics, lived in a Gakushuin University faculty dormitory in Tokyo with his family, including Crown Princess Kiko before she married Crown Prince Fumihito in 1990.
The couple met at Gakushuin University, which was originally created for the Japanese peerage, when they were students.
After graduating from the University of Tokyo's Faculty of Economics in 1964, Kawashima went on to obtain a master's degree in economics at a graduate school of the university, Japan's most prestigious academic institution.
Kawashima then continued his studies abroad. In 1971, he earned a doctorate from the University of Pennsylvania in the United States. The following year he taught at the Wharton School of the University of Pennsylvania before moving back to Tokyo.
In 1973, he became an assistant professor of economics at Gakushuin University and was promoted to professor in 1976.
For two years from 1977, Kawashima also conducted research at the International Institute for Applied Systems Analysis in Austria. Former princess Mako Komuro stayed at his friend's home in the suburbs of Vienna during a summer vacation when she was 14.
The government's top spokesman, Hirokazu Matsuno, lauded Kawashima for his humanitarian work installing clean water and sewage infrastructure in mountainous northern Thailand with his students, as well as his contributions as a member of an advisory panel to the Ministry of Land, Infrastructure, Transport and Tourism.
"I'd like to offer my heartfelt condolences and prayers," the chief Cabinet secretary told a press conference.