A brother and sister leave the big city to live with their veterinarian father when their mother is hospitalized. As they are adjusting to their new life filled with natural beauty, they adopt an abandoned puppy. When it is discovered that the puppy is actually a wolf, they choose to return the baby wolf to its mother in the forest rather than let it live a life in captivity.
It is 300 years into the future. Earth's environment had been devastated by mankind's own foolish plans and humankind is beleaguered by the sentient forests which they have awoken. The world balance is tipped when a young boy named Agito stumbles across a machine that glowed in a strange blue hue inside a forbidden sanctuary.