According to temple tradition, Kashozan Ryuge-in Miroku-gokoku-ji was founded in the first year of Kasho (848) by Ennin (Jikaku Daishi) of the Tendai sect, though its actual establishment is believed to be from a later period[1]. In the second year of Kōshō (1456), Tenson Keijun revitalized the temple and converted it to the Sōtō sect. During the Edo period, it became a prayer site for Tokugawa Ieyasu, achieving the prestigious status of holding a red seal estate of 100 koku and the formatting equivalent of 100,000 koku[1].

At the center of the tengu faith here is Tenson's chief disciple, Chūhōson. The custom of dedicating tengu masks is said to have originated from the legend that this monk, who guided practitioners with his supernatural powers, ascended to heaven as an incarnation of Kasho Buddha and left a tengu mask behind[1]. Worshippers first borrow a tengu mask from the Chūhōdō and take it home; when they visit next time, they return the borrowed mask along with a newly purchased one from the temple gates, offering both to the temple before borrowing yet another mask. This unique custom of "borrowing and returning masks" continues to this day[1]. The Great Tengu Mask in the Chūhōdō was originally dedicated to pray for victory in battle and traffic safety. Additionally, the Zazendō (Meditation Hall) houses the "All Wishes Fulfilled Great Tengu," dedicated in 1983, which is paraded as a portable shrine during the Numata Festival[1]. Situated about 16 kilometers north of central Numata, Mount Kasho continues to draw worshippers as a sacred mountain of the tengu[2].