Idoji (井戸寺) is temple 17 of the Shikoku Pilgrimage. It is located in Tokushima City, Tokushima Prefecture. The principal image (deity) of this temple is Shichi Butsu Yakushi Nyorai (七仏薬師如来).
There's a well on the temples grounds. Legend says that Kobo Daishi dug it in one night using his priest's staff. You can buy a small bottle of water from the well as a souvenir. It's supposed to be lucky if you look down into the well and you can see your face.