Sentinel Mountain is a 239-meter-high hill on the border of Pibu Town and Asahikawa City, with a total area of 225 hectares. It is believed to be derived from the Ainu word tuk-so, meaning "sticking out" or "place.
It is covered with thickets of deciduous broad-leaved forests of Quercus crispula, Japanese white birch, maple, and other trees, and is home to about 1,700 species of living creatures.
In early spring, the forest floor is covered with spring plants such as katakuris, ezo-engosaku, and figs, and the large colony of katakuris in particular is widely known as one of the largest in Japan.