Ryozenji is a temple belonging to the Koya school of the Shingon sect. The temple is dedicated to Gotama Siddhattha. It is the first temple on the Shikoku pilgrimage.

The Emperor Shōmu initiated construction of this temple after its inauguration by Gyōki Bosattsu in the Tenpyo period. In 815, Kōbō Daishi stayed here for 21 days and practiced his ascetic training. Later he invoked the creation of the 88-temple Shikoku pilgrimage. It is believed that during his training, he carved the Gotama Siddhattha figure, marking it as the first point on the pilgrimage. He founded schools that could teach the Taizoukai Mandala of the Dainichi Nyorai buddha in the Shikoku area. Each of the four regions of Shikoku was to establish schools of religion, training, Buddhahood and Nirvana.

He founded a total of 88 schools. Ryozenji was destroyed by fire at one point, but rebuilt and remains today a magnificent example of architecture.

Nowadays it is known as the starting point of the Shikoku pilgrimage. Throughout the year, it is crowded with pilgrims wearing the sedge hat and white costume of the henro.