Shikoku Pilgrimage
Going on a pilgrimage in Shikoku means visiting the 88 temples affiliated with Kobo Daishi (each temple has a number associated with it). If you go on foot, it would take about 40 days, even if you manage to walk 30km a day. There are bus/cab tours available, and people use their own cars/bikes as well.
You’re not obligated to visit the temples in order, and you can split your pilgrimage into several tours.
In the J-horror novel/movie “Shikoku”, going on the pilgrimage in reverse order was supposed to bring the dead back to life, but in reality, going in reverse order is supposed to be three times as worth as going in regular order, because of its difficulty.