Okuno-in is a quiet sacred site located halfway up the mountain from the main hall of Onsen-ji Temple. It is a special place for Onsen-ji Temple ascetic monks to conduct spiritual training, and also a space for general visitors to purify their minds and bodies and reflect on themselves in nature. Surrounded by the rich nature of the mountains, this sacred site offers tranquility and peace of mind to visitors and symbolizes the culture of faith and healing in the Kinosaki spa resort. The building itself follows the ancient tradition of Buddhist architecture and has a simple yet solemn appearance. Thus, Okunoin is a special place that combines historical and religious backgrounds with nature, and is one of the highlights that should not be missed when visiting Kinosaki Onsen.