Natsuo Yamaguchi

is a Japanese politician who served as the chief representative of Komeito from 2009 to 2024. He is a member of the House of Councillors since 2001 and previously served in the House of Representatives from 1990 to 1996.

Early life A native of Nakaminato (now Hitachinaka), Ibaraki and he was raised in Hitachi until his graduation from public senior high school. His mother was a teacher of the elementary school. After graduating from the University of Tokyo with a B.L. degree in 1978, he became a lawyer in 1982.

Political career Yamaguchi was elected to the House of Representatives for the first time in 1990. After losing his seat in 1996, he ran unsuccessfully for the House of Representatives in 2000. In 2001, he was elected to the House of Councillors for the first time. He was appointed chairman of the policy research council in August 2008. Komeito suffered a major defeat in the 2009 general election, losing ten seats, including party president Akihiro Ota and secretary general Kazuo Kitagawa. On September 8, Yamaguchi replaced Ota as president. He had been chosen through a process centered on party heavyweights Takenori Kanzaki and Chikara Sakaguchi.

Yamaguchi's first term as party leader expired in September 2012, and he was re-appointed unopposed for another two years on 22 September 2012. No vote was required, as he was the only candidate. He has continually been reelected since then.

After fifteen years leading Komeito, Yamaguchi stepped down in September 2024 and was succeeded by Keiichi Ishii.

Yamaguchi has come out in support of the selective surname system for married couples and same-sex marriage, as well as voting rights for permanent foreign residents.