Yamagata was a samurai of the Choshu region, a statesman and chief founder of the modern Japanese army. He studied military science in Europe and returned in 1870 to head the war ministry. Strongly influenced by Prussian military and political ideas and favoring military expansion abroad and authoritarian government at home, he supported Japanese military control of Taiwan, Korea, and Manchuria. As home minister (1883–87) he dissolved the new political parties and repressed the agrarian movement. As premier, he ruled that only an active military officer could serve as war or navy minister, a rule that gave the military control over any cabinet. From 1900 to 1910 he opposed Hirobumi Ito, leader of the civilian party, and exercised influence through his protégé, Taro Katsura. As president of the privy council from 1909 to 1922, he was the power behind the throne and the leading advocate for higher military appropriations.
Yamagata is the man who comes in search of Kenshin and offers him a place in the army in episode 3 of the anime. Kenshin refuses the offer and many other offers. He is also the one who convinces an ailing Kenshin in Seisouhen to go to China to help raise the moral of the troops during the Sino-Japanese war.