I don't know. I have trouble believing that even the Japanese, who apparently delight in cruelties, would be so cynical as to hurt a bunch of animals in the process of making a movie that celebrates them. It smacks of Western bigotry to assume otherwise.
A few years ago, a few of my friends got a whole lot of beer and watched this DVD. It was a raucous good time, I don't care how many dead animals it took. Try it at home with your friends, take a drink every time you think an animal died to get whatever shot they needed. You'll be drunk in the first ten minutes.