Hachi: A Dog's Tale description:

Commuting by train, music professor Parker Wilson finds an Akita puppy, whose cage broke unnoticed during shipping, leaving his destination unknown, and since the station can't care for it and the dog catcher warns even such cute ones may not be adopted in the two weeks allowed, he kindly takes it home. His bossy, jealous wife Cate initially makes Parker swear it won't stay, but by the time it's clear nobody will claim him and no adoption candidate is found, she agrees to keep the dog, who won over their daughter Andy and her fiance Michael at first sight. Parker's Japanese college friend Ken inspires naming the pup Hachi(ko), and is pleasantly surprised when Parker successfully tackles the challenge to get it to fetch, which Akitas don't usually do. Hachi makes a habit of waiting for his equally doting master at the station every evening, but after a cardiac crisis, Parker dies. Hachi refuses to accept this, being moved to Michael's home as Cate moves out, waiting for a master who can never come home again, by now collectively adopted by sympathizing town-folk. The story is told in flashbacks as class assignment 'my hero' by Michael's teen son Robbie, who also gets an Akita puppy.