, also known as , was a Japanese daimyà  in the Shikoku region in the late Edo period. He was usually referred to as Lord Yà Âdà  in Western accounts.
Yamauchi was the 15th head of the Tosa Domain. He opposed the treaties of the Ansei era. In 1859, he was forced to retire.
In 1862 he was appointed sanyo (Ã¥ÂÂä¸Â).
After the assassination of his favourite Yoshida Tà Âyà  in 1862, he ordered an investigation into the local anti-foreigner samurai groups, suspecting them of terrorism. These efforts culminated in the arrest and subsequent suicide of political rogue Takechi Hanpeita, who ordered the hitokiri Okada Izà Â, in 1865. In 1867 he advised Shà Âgun Tokugawa Yoshinobu to carry out Taisei Houkan (大æ¿å¥ÂéÂÂ), the return of power to the Emperor, which he carried out later that year.
In 1871, Yamauchi was appointed governor of the new Kochi Prefecture.