Male or female or both playing the role of Hachi?
Sometimes it seems to me that they used two dogs in this film (can't see the dog credited on IMDB or even a handler - maybe I'm not looking in the right place). Sometimes it's a definitely male dog with a tail that curls tightly over its back. Other times the tail droops down, and it looks like a female dog (two dark holes under the tail - isn't that a female?).
OK, I don't mean the old version of the dog, just the younger one romping around with Richard Gere.