In April 2011, he ran in the Saitama Prefectural Assembly election with the LDP's official approval and was re-elected without a vote.

[6] Nonaka was elected in Saitama 12th district after defeating Morita and Hiranao Honda, the former Democratic Party of Japan's former parliamentary secretary for Economy, Trade and Industry.

Although Toshikazu Morita, who ran for the PFG, appointed a former member of the LDP as the top adviser to the camp to expand the support of the conservatives,[8] Nonaka won.

[12][13] He was reappointed as Parliamentary Secretary to the Minister of Agriculture, Forestry and Fisheries in the Fourth Abe Cabinet, which was established after the election.

[14] In the 2021 Japanese general election, veteran party members such as Shigeru Ishiba, Yuko Obuchi, and Toshimitsu Motegi prematurely celebrated his re-election,[15] but lost to Morita, who won the race by a narrow margin.