Katte ni Shirokuma (1987)

Whatever, White Bear

Shiro is a dim-witted albino bear who lives with his mother and siblings in a remote forest, fishing and hunting for food on a daily basis. One day, a chance encounter with a tortoise leads the family to take an unexpected adventure far from their home. As they encounter various mysterious artifacts on their way back to the forest, they unexpectedly stumble upon a peculiar and unique sight: an abandoned city. [Written by MAL Rewrite]