Hara Kei, also known as Hara Takashi, was the first commoner to become prime minister of Japan.
He served as a government bureaucrat before becoming Home Minister in 1906. During his term in that position (until 1908), he strengthened his political party, the Seiyûkai, by attracting support from amongst the bureaucracy. He also placed loyal members of his party in positions as prefectural governors, and attracted others to his side by offering them policies and decisions that would specifically benefit their local/regional constituencies.
References
- Conrad Schirokauer, David Lurie, and Suzanne Gay, A Brief History of Japanese Civilization, Wadsworth Cengage (2013), 202.