Ishii was returned to the House of Representatives in the July 1986 general election, gaining the most votes in the Hyogo 1st district and regaining his seat from Nagae.

Despite the loss Ishii was able to retain a seat in the House as a member for the Kinki proportional representation block.

At the September 2005 general election Ishii lost to the LDP's Masahito Moriyama and was also unsuccessful in gaining a PR seat.

Ishii contested the July 2007 election for the House of Councillors, winning one of 48 seats in the national proportional representation block.

Ishii said the situation created a great problem for democracy in Japan and invited three former Komeito party members and Soka Gakkai Honorary President Daisaku Ikeda for an intensive deliberation on issue of politics.