In America, if you count to 5 on the hand, we start with a fist. Then, extend the index finger(pointing finger) for 1 and after, extend each finger in sequence, finishing with the thumb at 5 with an open palm.
In Japan, many people do almost the opposite. They start with an open palm, bend the thumb for 1, then the index finger for 2 and so on, finishing with the pinky at 5 with a fist. Again, my wife objects saying not all Japanese count like that and many do the American way. But, I have seen this so many times in my classes or on TV. It's very common. And, I have never, ever seen this way to count in America. Personally, I can't count like this. It doesn't feel natural. If I don't look,
I can't remember what number I'm on. This way of starting with the thumb might come from the fact that the thumb is known as the "Father finger" or "Parent finger" and is considered the most important. Japan is a country where honoring one's parents and ancestor worship are extremely important.