After graduating from Nihon University's engineering department, he joined Soka Gakkai and, as a close aide of Daisaku Ikeda, he supported the shakubuku movement of confrontational proselytisation.

In April 1963, he won a seat in the Tokyo Metropolitan Assembly representing the Shinjuku ward, this time as a candidate for the Komei Political League, the predecessor group to Komeito.

In July 1989, Fujii helped contribute to the success of the Japan Socialist Party at that year's metropolitan elections, and also was appointed the leader of the Assembly's deliberation group.

As early as 1995, Fujii had pondered the possibility of an LDP-Komeito coalition, something which would later come to fruition a year after his tenure as party chairman ended.

In the 2005 Tokyo prefectural election that was held in July, he turned over his power base to the younger candidate Masami Yoshikura and retired from the political world.