Cultural differences

This year, I made a lot of friends at kanda, and felt some cultural differences.
The most biggest difference was relationship between boys and girls. In America, it was very normal that boys and girls hug each other to show their good relationship in public. They also put their arms around friend's shoulders when they are talking on a sofa. These are not common in Japan, so I was surprised at it. In Japan, boys and girls don't hug and don't put their arms on friend's shoulders.Japanese sometimes do those things, especially when they are drinking., but it's not usual.