Asosanjo Jinja: The Shrine on the Mountaintop
Aso Shrine was founded more than 2,000 years ago, in 281 BCE. It consists of two shrines: the lower shrine (gegu) on the caldera floor in the city of Aso, and this, the upper shrine (jogu), a little more than 100 meters below the volcano crater. The crater itself is the object of worship. The official name of this upper shrine is Asosanjo Jinja, literally “Aso Mountaintop Shrine.” The present building, which was damaged in the eruptions that accompanied the 2016 Kumamoto earthquakes, is a concrete structure built in 1958.
The primary purpose of Aso Shrine was to keep the volcano deities happy so that Mt. Aso would not erupt and harm local crops, livestock, and people. The shrine priests would inspect the pond at the bottom of the crater, which represented the “mood” of the deities, and inform the court in Kyoto of any changes. If the water was seen to be behaving in a way that augured ill for Aso and for the country (an eruption was regarded as an omen of nationwide catastrophe), other shrines around Japan would be ordered to pray hard to prevent an eruption. Historically, the volcano worship at Mt. Aso was so important that it was mentioned in a seventh-century Chinese history book, as well as Japanese chronicles written in succeeding centuries.
Volcano worship continues to this day, with the crater-calming ritual conducted at the shrine every year in early June. The priests chant a Shinto prayer and fling wooden wands decorated with white zigzag paper streamers into the crater as offerings to the deities.