Kyoudai Koguma

Fuente: AniList

One spring day, little birds are singing and frogs are dancing. A mother bear in the cave tells her children to play outside, but also reminds the two brothers to be careful of the terrible humans. While they are sumo wrestling and eating honey, a hunter tries to shoot the bears. The two brothers see a human for the first time. They manage to find their way to the cave where the mother bear awaits them. They are amazed that the human walks upright. The mother bear teaches her two boys how to do it. Swallows and cranes fly away, summer goes by, and fall deepens. As a result of their efforts, the mother bear and her children master how to walk upright.