If you're looking for anime similar to Huckleberry no Bouken Movie, you might like these titles.
In the late 19th century, Huckleberry ‘Huck’ Finn lives alone in a tree house in the countryside of Mississippi due to family problems, carefree as a bird – regardless of what the lovely Becky thinks of his actions. Along with his best friends Jim, a runaway slave living with the Widow Douglas; and Tom, a boy who follows him everywhere, Huck constantly has fun, often ending up in a mess that the trio must solve together. What adventures await these friends?
White Fang is born on the plains of Alaska to a wolf father and a half-wolf, half-dog mother. One day he and his mother run into an Alaskan inuit boy Mit-sah, who has long dreamed of a dog of his own, and by a marvellous twist of fate, the wolves are taken in by him and his father. But life in Alaska is harsh for humans and wolves alike, and as winter comes, hardships lie in waiting for White Fang and Mit-sah. Facing the extreme coldness of their habitat and that of humans' greedy hearts, the two journey towards what they hope to be a happier environment.
Since the death of their parents, Tom Sawyer and his academic brother Sid have been raised by their aunt Polly in a small village called Saint Petersburg. Tom is a disobedient boy; he gives his aunt a hard time, ditches school to go fishing in the Mississippi River, climbs trees, and plays pirate games with his friend Huck. Although Tom usually does not attend school, he is quite popular among the pupils; even Tom’s crush, the pretty Becky, grows fond of him. Without a care in the world, Tom leads his friends into adventures; from catching boars or solving murders, there’s never a dull day for the intrepid Tom!