Kongo Sanmai-in sits slightly apart from the main tourist circuit, near the entrance to the Okunoin cemetery. The temple was founded in 1211 by Hojo Masako, a pivotal figure in medieval Japanese history, to pray for the souls of her husband and son — both shoguns of the Kamakura period. The three-storey pagoda, one of the oldest structures on Koyasan, is a designated National Treasure and dates from the early thirteenth century.
The grounds contain a fine collection of stone lanterns and graves, and the main hall houses some remarkable Kamakura-era Buddhist statues. Because it is less visited than the main complexes, Kongo Sanmai-in has a genuinely contemplative atmosphere. It also offers shukubo temple lodging, with notably good shojin ryori cuisine. Admission is around ¥500.