Aso's caldera is one of the largest in the world, 18km from east to west, 25km from north to south. In the plain that spreads over a vast caldera created by four huge pyroclastic eruptions, about 50,000 people live with the volcano, and the surrounding area has been handed over by the people for over 1000 years The vast grassland that is maintained by and the rich land that has been nurtured by the improvement of farmland over the years spreads and rich crops are growing.

https://en.wikipedia.org/wiki/Aso,_Kumamoto