Mt Aso National park is located in the Kumamoto Prefecture and is one of the largest calderas in the world. It is 17 Km across from east to west, 25 km north to south and has an area of roughly 350 square km.
The group of five volcanoes in the centre of the caldera, that includes  Mt Taka, Mt Eboshi, Mt Kijima, Mt Neko and the still very active Mt Naka  is referred to as Mt Aso. There is no actual Mt Aso
Unfortunately the day we were there was a very cold cloudy day but the view from the lookout was still spectacular.

Yes there are people living down there in a caldera amongst volcanoes.

Yuko Ura standing at the lookout.