Natsuo Yamaguchi was born in what is now Hitachinaka City, Ibaragi Prefecture, on July 12, 1952. Having graduated from University of Tokyo's Faculty of Law in 1978, Yamaguchi began practicing as an attorney in Tokyo from 1988. In 1990, he successfully ran on the party ticket in the House of Representatives election, winning two terms. He then ran as a New Komeito candidate for the House of Councilors in 2001. Prior to his appointment as New Komeito Chief Representative in September 2009, Yamaguchi served as Parliamentary Vice-Minister of the Defense Agency and chaired New Komeito's Policy Research Council, the party's top policymaking organ, since 2008. Considered by his peers both within the party and in parliament as an authority on a wide range of policy issues, Yamaguchi led the Japanese government's effort to support demining programs worldwide and ban cluster bombs. Among his domestic successes have been initiatives to earthquake-proof public schools and to settle a longstanding air pollution lawsuit against the government in favor of the plaintiffs. Yamaguchi currently lives in Tokyo with his wife and has three children, one daughter and two sons.

Keiichi Ishii was born in Tokyo, on March 20, 1958. He graduated from Tokyo University in 1981, having majored in Civil Engineering. After serving in Ministry of Construction for 12 years, he successfully ran for a seat in the House of Representatives in 1993. In 2000, he won a seat in the House of Representatives through the North Kanto proportional representation bloc, serving tenth terms. Prior to his appointment as Secretary General in September 2020, Ishii was apppointed to Minister of Land, Infrastructure, Transport and Tourism in 2015, serving for four years. He serverd as Party Policy Research Council Chiar in 2010. Ishii currently lives in Tsukuba City, with her wife, and has a son.