The Shimokita Peninsula is a broad thumb of land at Honshu's northern tip, curling around Mutsu Bay and up toward Hokkaido. It is a wild place. Here you can find feral horses, the world's northernmost wild monkeys, some of Japan's last remaining wilderness -- and a holy mountain, Osorezan.

As you approach on the mountain roads you can feel sulfur in the air. When you arrive, a moon landscape spreads out before you. The mountain is a composite volcano. In the caldera is a lake, but the water is as clear as glass while the streams feeding it are bright yellow with sulfur. Only one kind of fish can live in this acid water, a variety of dace or chub called the ugui (Tribolodon hakonensis) which has become the subject of much research.