I read this story in the Japanese news a long time ago..
If I remember right, Mari was found as a stray puppy and kept outdoors because the father did not really like dogs. (common in Japan, sadly). A few years later, Mari gave birth to 3 puppies on the day of the Niigata earthquake.. in this little movie they show the puppies as older puppies, but in real life they were 1 day old.
When the earthquake happened, her puppies could not yet walk nor were their eyes open. Mari managed to escape her collar after injuring herself pretty badly...
The rescuers did leave Mari behind but some time later the family was able to return to their abandoned town where they did find Mari, who did successfully keep 3 puppies alive for 2 weeks (although she became very skinny) probably by hunting small animals herself.
Anyway, that is the whole story as I remember it. It is a nice story!