Yamaji Motoharu in the context of "Viscount"

The Tosa Domain (土佐藩, Tosa-han) was a feudal domain under the Tokugawa shogunate of Edo period Japan, controlling all of Tosa Province in what is now Kōchi Prefecture on the island of Shikoku. It was centered around Kōchi Castle, and was ruled throughout its history by the tozama daimyō Yamauchi clan. Many people from the domain played important roles in events of the late Edo period including Nakahama Manjirō, Sakamoto Ryōma, Yui Mitsue, Gotō Shōjirō, Itagaki Taisuke, Nakae Chōmin, and Takechi Hanpeita. Tosa Domain was renamed Kōchi Domain (高知藩, Kōchi-han) during the early Meiji period until it was dissolved in the abolition of the han system in 1871 and became Kōchi Prefecture.

The Port Arthur massacre (Chinese: 旅順大屠殺) took place during the First Sino-Japanese War from 21 November 1894 for three days, in the Chinese coastal city of Port Arthur (now Lüshunkou District of Dalian, Liaoning), when advance elements of the First Division of the Japanese Second Army under the command of General Yamaji Motoharu (1841–1897) killed somewhere between 2,600 civilians and 20,000 people including Chinese soldiers, although one eyewitness reporter estimated a total death toll of 60,000, including civilians, soldiers, and residents of the outlying rural district.

Reports of a massacre were first published by the Canadian journalist James Creelman of the New York World, whose account was widely circulated within the United States. In 1894, the State Department ordered its ambassador to Japan, Edwin Dun, to conduct an independent investigation of Creelman's reports.