Born in Kirishima, Kagoshima, Ozato's first electoral victory came at the prefectural level in 1959.

In January 1995, the Great Hanshin earthquake hit Japan, and Ozato was reassigned to handle disaster relief.

[4] Ozato was a member of the Kōchikai faction of the Liberal Democratic Party, originally under the leadership of Kiichi Miyazawa.

[6][7] Ozato succeeded Koko Sato as director of the Management and Co-ordination Agency in 1997.

[8] Ozato was appointed to lead the Liberal Democratic Party's Executive Council in 2000, replacing Yukihiko Ikeda,[9][10] but stepped down at the end of the year.