[1] Adachi was born in Sakyo-ku, Kyoto, and grew up in Fukui, Sakai, and Takatsuki.

He graduated from the University of Tokyo and joined Sumitomo Corporation in 1983, where he worked on rail car exports to the United States.

He thereafter worked in the legal department of Sumitomo, and in the executive office of its Chinese subsidiary.

[2] He ran as a Liberal Democratic Party candidate for the House of Councillors in the 2007 election but lost[3] He joined the law school faculty of Nihon University as an adjunct professor in 2008.

[6] He was appointed as a vice-minister for the Cabinet Office and Ministry of Land, Infrastructure, Transport and Tourism in 2018 under Prime Minister Shinzo Abe.