Natsuki Uchiyama (内山 奈月, Uchiyama Natsuki, born 25 September 1995) is a Japanese copywriter and former idol. She is a former member of the Japanese idol girl group AKB48, where she was part of Team B.

Uchiyama passed AKB48's 14th generation auditions on 13 May 2012. She debuted on 9 July 2012.^{[citation needed]} In August 2013, she was promoted to the newly formed Team 4. In February 2014, during the AKB48 Group Shuffle, it was announced that Uchiyama would be transferred to Team B. In April 2014, Uchiyama enrolled in Keio University.^[1]

In the 2014 AKB48 Group general election, Uchiyama ranked for the first time at 63rd place.^[2]

Uchiyama's special skill as an idol was to recite articles of the Japanese Constitution. In July 2014, she collaborated with Shigeru Minamino [ja], then an associate professor at Kyushu University School of Law, to write a book titled Constitutionalism: The Essence Unwritten in the Text (憲法主義: 条文には書かれていない本質, Kenpō shugi: jōbun ni wa kaka rete inai honshitsu) regarding the Japanese Constitution.^[3] They co-wrote the book with the hope that Japanese teenagers would get a basic grounding and become interested in constitutional discourse, since although the voting age in Japan has been lowered to 18 years old, education on the matter was considered lacking.^[4]

On November 1, 2015, she announced her graduation from AKB48,^[5] and she completed her final activity as a member on February 21, 2016.

As of October 16, 2017, she was signed to Horipro and was billed as a "Constitutional Idol" (憲法アイドル, Kenpō aidoru).^[6]

From January to March 2018, she was a participant in Parliament Member GO (議員ＧＯ, Giin Go), a political variety show inspired by Pokémon Go, which was broadcast on the Internet television channel AbemaNews [ja].^[7]

In March 2018, she graduated from the Faculty of Economics of Keio University and left Horipro. She joined the Hakuhodo advertising agency the same year.^[8] In 2020, her team won the Grand Prix in the Brain Online Video Award competition.^[9]

• "Constitutionalism: The Essence Unwritten in the Text" (憲法主義: 条文には書かれていない本質, Kenpō shugi: jōbun ni wa kaka rete inai honshitsu) (2014), ISBN 9784569764801, co-authored with Shigeru Minamino