The life of a man, transitioning from a hunter-gatherer existence in the mountains to a life in the farm. One day, he comes across an ox, which somehow, he succeeds in leading back to his home. He lives with the animal, which becomes his companion in a life of changing seasons.

As a tunnel construction project threatens the natural order of one of Japan's last untouched regions, an old man and his granddaughter Haruna's humble lifestyle begins to influence the outlook of a man from Tokyo.

A case-hardened cop is pitted against a young eco-terrorist. The title "island" is an artificial construct in Tokyo Bay, a mountain of garbage, a by-product of Japan’s economic boom years. The film’s protagonist Alan works there, almost buried under society’s detritus; his growing obsession with the search for “what has been lost” turns him into a "dangerous" activist. He targets the industrialist Wada, whose chemical factory secretly discharges toxic waste into the environment. But the cop Terayama, who thought he’d seen it all, starts researching eco-activism and soon suspects the haunted, taciturn young man he’s encountered in the neighborhood.