“Dogo, as already indicated, is almost invariably preferred to Matsuyama by Japanese travellers visiting these parts. Indeed it is, next to Konipira, the favourite place in Shikoku on account of its mineral springs, excellent inns, and pretty park.
“The baths, which are public, are of three different degrees of strength, the two stronger being resorted to by patients suffering from cutaneous diseases, while the weakest (Ichi-no-yu) is patronised by pleasure-seekers in good health, so that no unpleasantness need be apprehended from bathing in it. The bathers are said to be over 1,000,000 in one year.
“Dogo is probably the most ancient spa in the empire. According to the Japanese mythology, two gods — Onamuji and Sukuna-bikona — bathed here, and their example was followed by five Mikados from the legendary period downwards.
“Earthquakes have interrupted, but never entirely stopped, the flow of sulphur water, which, however, is not forthcoming in sufficient quantities to permit of its being led in to the various inns and private houses.”
– A Handbook for Travellers in Japan, including the Whole Empire from Yezo to Formosa, by Basil Hall Chamberlain & W.B. Mason, 1901
“Matsuyama’s star attraction — Dogo Onsen (also known as Iyo no onsen) — is thought to be the oldest spa in Japan, a claim reinforced by its mention in the second oldest book of Japanese history, Nihon Shoki (720 AD). The public bathhouse is a good time in any season, drawing serious hot spring enthusiasts and newcomers alike to its steamy waters.
“Dōgo Onsen was the favorite retreat of writer Natsume Sōseki (1867–1916) when he was working near Matsuyama as a teacher in what was, at the time, rural Shikoku. In Soseki’s loosely autobiographical novel Botchan, the eponymous main character is a frequent visitor to the springs, the only place he likes in the area.
“Modern haiku poet Masaoka Shiki, a noted critic of Matsuo Bashō (1644–1694), was a resident of Dōgo Onsen. His poems are prominently inscribed in many places around town:
Ten year’s sweat
washed away
back at Dogo Onsen.“
– Wikipedia