Hokkaido is Japan's northernmost - and wildest - island, a place totally unlike the rest of the country. Every year, it swings from a bitter Siberian winter into the warmth of a Mediterranean-like summer, whenthe thaw reveals a landscape changed beyond all recognition. It takes tough animals and tough people with real ingenuity to survive, and even thrive, in this ever-changing place.

In the far south west of Japan, there is a chain of islands stretching towards the tropics - a place where all life is influenced by the power of the sea, and where volcanoes and typhoons are forces to be reckoned with. The journey begins at an island at the top of the chain and travels south, revealing unexpected stories of isolation, unique wildlife and unsolved mysteries.

The central island of Honshu is home to over 100 million people, and its biggest city, Tokyo, is one of the largest urban metropolises on earth. But it has a wild heart - most of Honshu is mountainous.

This wilderness is home to an astonishing range of wildlife - black bears, monkeys, exquisite fireflies and even cow demons. But all across this island, from the mountains to the edge of the sea, people and nature are drawn together in the most unexpected ways.