A Tale of Ululu's Wonderful Forest(ウルルの森の物語)

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.