Tatsuhiko Kawashima, the father of Crown Princess Kiko and a professor emeritus at Gakushuin University, has died, sources said Thursday. He was 81.

His death comes not long after the marriage of former Princess Mako, one of his granddaughters, to her commoner boyfriend Kei Komuro on Oct. 26.

Kawashima was admitted to a Tokyo hospital on Oct. 19. Crown Princess Kiko and her two daughters — Mako and Princess Kako — visited the hospital to see him that day, according to the sources.

The Tokyo native is also the grandfather of Prince Hisahito, 15, who is second in line to the imperial throne.

Known for his frugal lifestyle, Kawashima, a professor of economics, lived in a faculty dormitory of Gakushuin University in Tokyo with his family including Crown Princess Kiko before she married Crown Prince Akishino in 1990.

The couple met at Gakushuin University, which was originally created for the Japanese nobility, 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. Mako stayed at his friend's home in the suburbs of Vienna during a summer vacation when she was 14.