Japan's poorest prefecture is Okinawa — and on Okinawa the poorest region lies along the northeastern coast blanketed by the dense Yanbaru jungle. Here, the villages of Higashi and Kunigami were the last areas on the island to receive electricity and running water. Until 1978, they lacked even a paved road.

Yet when it comes to biodiversity, this is one of the richest places on the planet, with almost a dozen unique species, including the noguchi gera, an endangered woodpecker that has become a symbol of the prefecture.

On a recent visit, the Yanbaru's bountiful nature lulls me into a sense of serenity — which soon proves false. Parked at a roadside stall of sugar-sweet pineapples for which the area is renowned, I watch chickens peck for grain while a wild boar and her two piglets nose through the nearby hibiscus bushes. The boar are the first to sense something is wrong. The mother squeals ,then butts her babies into the undergrowth just as three huge helicopters roar overhead, followed by a convoy of camouflaged trucks barreling down the narrow road. Suddenly it feels like the front line of a war zone.