Matsumae clan
This onsen is considered by Japanese to be one of the three major hot springs in Hokkaidō. Its origins are said to date back to 1653 when a lord of the Matsumae clan was healed of an incurable illness by bathing in its waters. Legend says that Seiryoin (清涼院), the 9th Lord of Matsumae Domain's mother, had him bathe for medical purposes in the Yunokawa Onsen in 1653. Having recovered from illness, and she had the Yakushido (薬師堂) rebuilt to honor his recovery and it was dedicated to Wniguchi (鰐口).