After graduating from Kyoto Prefectural Sonobe Junior High School in 1943, Nonaka worked for the Japanese National Railways (JNR) in Osaka, an office managed at the time by future prime minister Eisaku Sato.

[2] Later that year, in response to a demand for further apologies by General Secretary of the Chinese Communist Party Jiang Zemin, Nonaka described the issue as a "finished problem.

"[3] In 1998, Nonaka was named Chief Cabinet Secretary under Prime Minister Keizō Obuchi, where he wielded an unusual amount of power in this role.

[11] Following his 2003 departure from the Diet, Nonaka served as chairman of the National Federation of Land Improvement Industry Groups, a powerful supporter of the LDP.

[12] On 5 June 2013, Nonaka led a delegation including former Prime Minister Yukio Hatoyama to visit Beijing and confer with Liu Yunshan, a member of the Politburo Standing Committee of the Chinese Communist Party.

Nonaka told reporters that as a young politician in the 1970s, he had heard Kakuei Tanaka state that an agreement had been reached to shelve the dispute between Japan and China over the Senkaku Islands in order to normalize relations between the countries.

[13] Chief Cabinet Secretary Yoshihide Suga denied the claim as "baseless" and alleged that Nonaka had been influenced by "Chinese hospitality.

"[citation needed] In 2017, Nonaka publicly criticized the LDP's plans to revise Article 9 of the Japanese Constitution, stating that "Japan should not go through the history of war again.