Sohei Kamiya (神谷 宗幣, Kamiya Sōhei; born 12 October 1977) is a Japanese politician who is the founder and leader of the political party Sanseitō. Kamiya has been serving as a member of the House of Councillors since 2022 through the Proportional Representation Block. He advocates "Japanese first" and anti-globalism.

A conspiracy theorist who promotes COVID-19 and vaccine misinformation, Kamiya gained international media attention while campaigning for the 2022 House of Councillors election due to his antisemitic rhetoric during public appearances and campaign rallies. He has been described as a controversial politician and his party a cult by his political opponents.

Kamiya was born in Takahama, Fukui on 12 October 1977. He graduated from Fukui Prefectural Wakasa High School, majoring in science and mathematics. He then entered Kansai University's Faculty of Letters, Department of History and Geography (now called the Department of General Humanities). He moved to Suita, Osaka after graduating from the same university in 2001. He became an English and history teacher at Fukui Prefectural Wakasa Higashi High School.

In 2002, he became an employee of Kamiya Store, a company run by his parents, and served as a store manager. In 2003, he made a short return as a teacher at Fukui Prefectural Wakasa Higashi High School. In 2004, he enrolled in Kansai University Law School's Legal Professional Training Course, completing his studies in 2007 and obtaining a Juris Doctor degree.

In the 2007 Japanese local elections, Kamiya ran for the Suita City Council and was elected. He was inaugurated as a councilor on May 27, 2007. Kamiya founded the regional political party Suita Shinsengai in the same year. In 2010, he became a representative of the Kansai State Politicians Federation. In June of the same year, he established the Ryōma Project (jp) National Association and assumed the position of chairman. In 2011, Kamiya was re-elected as a member of the Suita City Council. He was then elected as the Vice Chairman of the City Council.

In November 2012, Kamiya joined the Liberal Democratic Party and became the head of the party's Osaka 13th district (Higashiōsaka) branch, replacing House of Representatives member Akira Nishino. Kamiya then resigned from his seat in the Suita City Council to run for the 2012 Japanese general election, with then-LDP President and former prime minister Shinzo Abe personally campaigning on behalf of Kamiya, but lost to Koichi Nishino from the Japan Restoration Party.

In 2013, Kamiya founded "Grand Strategy Co., Ltd." (later renamed "Ishiki Kaikaku Co., Ltd."), which distributed online video content such as dialogues with conservative commentators and ran personal development seminars. The seminar featured lecturers who advocated conspiracy theories and spirituals. Around this time, he handed out his business cards to persons he became close to that read, "Let's do politics like One Piece."

In the 2015 Japanese local elections, Kamiya ran for the Osaka Prefectural Assembly as an Independent candidate for Suita's electoral district, but was defeated, placing 6th out of 6 candidates.