Mitsuzuka was born in the town of Misato, Miyagi prefecture, on 1 August 1927.

[5][6] He held significant posts in the LDP, including policy research council chairman and secretary general.

[7] The first head of this faction that occupies the right wing of the LDP[1] was Nobusuke Kishi, who was succeeded by Takeo Fukuda.

Mitsuzuka was one of the "big four" in the faction consisted of he, Masajuro Shiokawa, Mutsuki Kato and Yoshirō Mori.

[3] Mitsuzuka was appointed secretary general of the party by the LDP President Kono Yohei in 1996.

[1] Then he was appointed minister of international trade and industry in the same cabinet in a reshuffle on 28 December 1988,[15] replacing Hajime Tamura in the post.

Mitsuzuka was appointed minister of finance in the second cabinet of Ryutaro Hashimoto on 7 November 1996, replacing Wataru Kubo in the post.

[19] He resigned from office on 28 January 1998 to take responsibility for corrupt behavior by the officials at the ministry, although he was not personally involved in the incident.

[22] Mitsuzuka served as chairman of the Japan Palau Friendship Diet Representatives' Association.