As sekiwake of the East stands the spring of Nasu in Yashu (Tochigi Prefecture).
Nasu's waters rise at Yumoto, at the foot of Mount Nasu. A legend tells of its origin.
Long ago, in the reign of Emperor Jomei, a man named Kano no Saburo Yukihiro was hunting in the mountains of Nasu. He spotted a white deer and shot an arrow at it, but failed to kill it. The wounded deer fled deep into the mountains.
When Yukihiro followed it into the mountains, he found the deer soaking in hot water that welled up in a valley, healing its wound. Astonished at the water's wondrous power, Yukihiro told people about it. The spring found in this way, it is said, came to be called the "Shika no Yu," the Deer Spring.
Nasu's water is milky white with a strong smell of sulfur, and has long been known as a cure for illness. At Yumoto stands Onsen Shrine, dedicated to the god of the hot spring; it is said that Nasu no Yoichi prayed here before shooting the fan target at the battle of Yashima.
In the Edo period, travelers on the Oshu Highway and bathers from Edo came here, and at the Deer Spring people soaked up to their necks in the hot water, quietly counting the time.