Aso is a huge caldera of an ancient supervolcano that, as a result of its massive past super-eruptions collapsed onto itself, leaving an area of indented ground with a mountain range at its center which now holds an active crater. I rented a car and explored the area for 2 days.
Usa Jingu is one of the oldest and most important Shinto shrines in Japan. It is dedicated to Hachiman deity, and is the ancestor of all other Hachiman shrines.