Aso Kujū National Park

Listen first. Wind moves across open grass, and the grass answers with a long, dry hiss. Somewhere a cow shifts its weight. Far off, a thin plume of white steam rises from a grey mountain and drifts sideways. The air may carry a faint sharp edge, a little like a struck match. That is sulphur, and it tells you this landscape is still alive. You are standing inside a volcano.

Aso Kujū National Park stretches across the heart of Kyushu, Japan's southern main island. It covers ground in two prefectures, Kumamoto and its eastern neighbour, Ōita. The park was designated in 1934, in the very first group of national parks Japan ever created. That timing matters. Even then, people understood that this was not one mountain but a whole system of fire, grass, water and human work, and that it needed protection as a single place.

The centre of it all is the Aso caldera. A caldera is a vast hollow that forms when a volcano empties itself and the ground collapses inward. Aso's caldera is one of the largest in the world. It runs roughly twenty-five kilometres from north to south, and about eighteen kilometres from east to west. Geologists link it to a series of enormous eruptions, the last great one roughly ninety thousand years ago. Ash from those events reached far beyond Kyushu.

Here is the first surprise. The floor of this caldera is not empty wilderness. It holds towns, rice fields, schools, shops and a railway line. Tens of thousands of people live their whole lives inside the crater bowl. They drive to work under the old rim, which rises around them like a green wall. Few places on Earth ask people to make a home so directly inside a volcano, and here it feels almost ordinary.

Rising from the middle of the caldera are the Five Peaks of Aso. Taka-dake is the highest. Neko-dake, to the east, has a jagged, broken crest that stands out on the skyline. Then come Eboshi-dake and Kishima-dake, rounder and softer. And there is Naka-dake, the active one. Locals say that, seen from the north rim, the five peaks look like a figure of the Buddha lying down in rest.

Naka-dake is the reason people come from across the world. Its crater holds, at quiet times, a lake of milky turquoise water that steams and churns. The colour comes from minerals and heat. But this is a working volcano. Access to the crater rim opens and closes depending on gas levels and eruption warnings. Sometimes visitors can walk to the edge. On other days the road is shut, and the mountain is watched only from a distance.

Below Eboshi-dake lies Kusasenri, one of the most loved views in the park. The name means something like a thousand ri of grass, a ri being an old Japanese unit of distance. It is a wide, flat meadow, which is actually an old crater, with shallow ponds that collect rainwater. Horses often graze here, and in fine weather you may see visitors riding slowly across the grass. Nearby, the Aso Volcano Museum explains the geology in more detail.

Now the second surprise. These grasslands look natural, but they are not wild. They exist because people have kept them open for a very long time, by many accounts more than a thousand years. Each early spring, local communities set controlled fires across the slopes. This practice is called noyaki, or field burning. The fire clears old growth and stops forest from taking over. Without it, much of this open country would slowly turn to woodland.

The grass also feeds animals. The brown cattle of the region, known as akaushi, graze the slopes in the warm months. Farmers cut grass for winter feed and for compost on their fields. So fire, cattle and farming form one loop that shapes everything you see. When you look across a smooth green slope here, you are really looking at generations of shared labour, carried out year after year.

Off to one side of the main road stands Komezuka, a small, perfectly rounded cinder cone with a dent in its top. The name means rice mound. According to a popular legend, the god Takeiwatatsu, honoured at the nearby Aso Shrine, piled up rice here as a gift for hungry people. He then scooped a handful from the summit to share, leaving the hollow you can still see. It is a gentle story for such a fiery landscape.

The Aso Shrine itself sits on the caldera floor and is one of the oldest and most important shrines in Kyushu. In April 2016, a series of powerful earthquakes struck Kumamoto. The shrine's great two-storey gate collapsed. Roads, bridges and slopes across the region were badly damaged. Since then, the gate has been carefully rebuilt, and many routes have reopened. Recovery here is not a footnote. It is part of the living story.

Travel east and the park changes character. The Kujū mountains rise across the border in Ōita. Their highest summit, also called Naka-dake, is the tallest peak on the island of Kyushu. In early summer, the slopes turn pink and purple with Miyama Kirishima azaleas, a small mountain azalea that grows in dense mats. Below them lie high wetlands such as Tadewara, where boardwalks cross reeds and marsh grasses. Hot spring towns gather at the edges of the range.

Together, these places show one idea from many angles. The earth here is restless. It has broken open, collapsed, steamed and shaken, and it will do so again. And still people farm it, burn it, graze it and pray in it. For an editor's eye, that is the real story of Aso Kujū: not a scenic backdrop, but a long negotiation between human life and a volcano that never fully sleeps.

Before you move on, take one more slow look around you. Find the line of the caldera rim on the horizon, and trace it with your eyes. Notice the colour of the grass, whether it is spring black, summer green or autumn gold. Listen again for the wind. Then, as you walk away, remember that the ground under your feet is the floor of an ancient volcano, and it is still breathing.