Tradition relates that in 792, the year before establishing Enryaku-ji on Mt. Hiei, Dengyo Daishi Saicho entered the mountains of Koka for training, carved an Eleven-Headed Kannon from a sacred yew tree with his own hand, and enshrined it — the founding of Ichino-dera. As a temple linked to Saicho immediately before he founded the Tendai school, Ichino-dera became an important sacred site in the Tendai tradition.

According to temple records, Minamoto no Yoritomo, founder of the Kamakura shogunate, was among the medieval warrior lords who devoted themselves to Ichinodera in Koka. Along with the Ashikaga clan, Yoritomo's reverence helped sustain this ancient Tendai temple founded by the sage Saicho through the medieval period.