The circuit loops around the entire island of Shikoku through 88 temples plus an optional 20 "unnumbered" (番外 bangai) temples. All the temples are said to have been founded by monk and scholar Kūkai (空海), better known by his posthumous title Kōbō Daishi (弘法大師), who among his many achievements created the kanasyllabary, brought the tantric teachings of Esoteric Buddhism from China, developed it into the uniquely Japanese Shingon sect and founded Shingon's headquarters on Mount Koya near Osaka.

While most modern-day pilgrims (an estimated 100,000 yearly) travel by bus, a minority still set out the old-fashioned way on foot, a journey which takes about 60 days to complete. Pilgrims, known as o-henro-san (お遍路さん) or henro in Japanese, can be spotted in the temples and roadsides of Shikoku clad in a white jacket emblazoned with the characters Dōgyō Ninin (同行二人), meaning "two traveling together" — the other being the spirit of Kobo Daishi. Most (but not all) temples offer basic but affordable lodging for pilgrims.

Many henro begin and complete their pilgrimage by visiting Mount Kōya in Wakayama Prefecture, which was settled by Kūkai and remains the headquarters of the Shingon sect of Buddhism. The 21km pilgrim route up to the mountain still exists, but most henro use the train.

Completing the course the traditional way on foot is a serious undertaking that demands several months of time. Good physical fitness and stamina is required to endure the stress of constant walking up and down the hills of Shikoku, in the burning sun and the pouring rain.