Mitsuzuka was a leading member of the Liberal Democratic Party, being a member of the Seirankai. He was also Kokkai secretary. He served ten terms at the House of Representatives. He was first elected to the House in December 1972 from Miyagi Prefecture's No. 3 constituency. He held significant posts in the LDP, including policy research council chairman and secretary general. Mitsuzuka was a member of the Abe faction, headed by Shintaro Abe. The first head of this faction that occupies the right wing of the LDP was Nobusuke Kishi, who was succeeded by Takeo Fukuda. Abe was the third head of the faction. Mitsuzuka was one of the "big four" in the faction consisted of he, Masajuro Shiokawa, Mutsuki Kato and Yoshirō Mori. On 20 June 1991, Mitsuzuka became leader of the Abe faction in the LDP, inheriting it after Abe's death in 1991. On the other hand, he and Mutsuki Kato toughly struggled over the control of the faction, resulting in Matsuki's removal from the faction in 1991. His election as faction leader led to the collapse of the solid coalition between the Takeshita faction, led by Noboru Takeshita, and Abe faction in the party. The Abe faction was later renamed as the Mitsuzuka faction under his leadership. His faction became one of the five influential factions in the LDP at the beginning of the 1990s. In December 1992, the faction was the largest one in the LDP with 73 members. In 1996, his faction was still the largest one in the party with seventy-four members. The control of his faction was assumed by Yoshirō Mori by 1999. In 1991, Mitsuzuka ran for the LDP president, but lost the election, and Kiichi Miyazawa became the president of the party. In 1994, he ran for the prime ministership. However, due to the allegations of involvement in the construction scandals of 1994 his bid was not successful. Although he was not charged, criticisms about him became public. Mitsuzuka was appointed secretary general of the party by then LDP president Kono Yohei in 1996.
Ministerial career
Mitsuzuka's first ministerial post was the minister of transport in the cabinet led by Prime Minister Noboru Takeshita. He was in office from 1985 to 1986. Then he was appointed minister of international trade and industry in the same cabinet in a reshuffle on 28 December 1988, replacing Hajime Tamura in the post. Mitsuzuka was in office until 1989. He was appointed minister of foreign affairs in June 1989 in the cabinet headed by Prime Minister Sousuke Uno. When Mitsuzuka was in office, he harshly criticised the Japan firms, arguing that they created an image of Japan as "trying to make money like a thief at fire." His term lasted until August 1989. Mitsuzuka was appointed minister of finance in the second cabinet of Ryutaro Hashimoto on 7 November 1996, replacing Wataru Kubo. He resigned from office on 28 January 1998 to take responsibility for corrupt behavior by officials of the ministry, although he was not personally involved. Hikaru Matsunaga succeeded him as finance minister on 1 February 1998.
Other positions and retirement
Mitsuzuka served as chairman of the Japan Palau Friendship Diet Representatives' Association. He retired from politics in August 2003 due to health concerns.
Death
Mitsuzuka injured his back in June 2003, leading to deterioration of his health. He died of illness at a Tokyo hospital on 25 April 2004. He was 76.
