Oze occupies a high-altitude basin at roughly 1,400 meters, ringed by mountains that read like a geology textbook. To the north rises Mount Hiuchigatake, at 2,356 meters the tallest peak in the Tohoku region and the volcano whose ancient eruptions dammed the streams that created the marshland in the first place. To the south stands Mount Shibutsu at 2,228 meters, composed of serpentinite rock so unusual that climbing routes on it are restricted to protect the rare alpine flora. Between them stretches Ozegahara, Japan's largest highland marsh at approximately 8 square kilometers -- a peat bog that has been accumulating organic matter for roughly 6,000 years. The park itself spans 372 square kilometers across Fukushima, Tochigi, Gunma, and Niigata Prefectures, encompassing not just the marshes but the surrounding peaks and forests.

The story of Oze's survival is the story of the Hirano family. When a hydroelectric dam was first proposed in 1903, it would have flooded the entire marsh basin. The Hirano family, who owned land in the area, began decades of resistance. After World War II, a second dam project emerged, and botanist Hisayoshi Takeda joined forces with the family to fight it. In the 1970s, when road construction threatened to slice through the wetlands, a third generation of Hiranos led the opposition. Over the course of four generations, the family appealed directly to government officials, including the first director of the Ministry of Environment, blocking dams, roads, and development projects one after another. Their persistence helped transform Oze from a regional concern into a national symbol of environmental stewardship.

More than 900 species of vascular plants have been documented in Oze's wetlands. The spectacle begins in late May when mizu-basho -- white skunk cabbage -- pushes through the snowmelt in vast carpets of green and white that stretch to the horizon. By late June, watasuge (cotton grass) transforms the bog into what looks like a field of snow. July brings the nikko-kisuge, yellow alpine day lilies that give the marshland a warm golden cast, and the endemic bog asphodel adds a buttery accent through August. Visitors walk on elevated boardwalks that protect the fragile peat beneath, winding through a landscape that feels less like a park and more like a living botanical archive, each season layering a new palette over the ancient bog.

When Oze was formally designated as Japan's 29th national park on August 30, 2007, it was the first new national park the country had created in two decades -- the last being Hokkaido's Kushiro Wetlands in 1987. The park's territory was carved partly from the existing Nikko National Park, recognizing that the Oze marshlands deserved their own identity rather than serving as an appendage to a park known primarily for its ornate Tokugawa-era shrines. The designation also brought the area under Ramsar Convention protection as a wetland of international importance. In Gunma Prefecture, Oze holds a place of such cultural significance that it appears on the 'se' card of the Jomo Karuta, a traditional card game used to teach children about their region's treasures.

Reaching Ozegahara requires effort. The marsh boardwalks themselves are flat and gentle, but accessing them means mountain hiking with real elevation changes -- a round trip of six to eight hours from trailheads like Hatomachi Pass. This is deliberate. There are no roads into the marsh, no parking lots at its edge, no gondolas descending from the ridgelines. The difficulty of access is itself a form of conservation, filtering out casual traffic and preserving the silence that makes Oze feel remote even though Tokyo lies only 150 kilometers to the south. For those who make the walk, the reward is standing in the landscape that Nakanishi wrote about in 1949 -- mist settling into the valleys, white blossoms catching the light, and the understanding that this ancient place survives because ordinary people decided it mattered enough to fight for.