This may not come as that big of a surprise, but physical touching is not really a thing in day-to-day life in Japan. For example, friends and families aren't greeted with hugs and kisses in Japan and doing so would seem out of the ordinary. This one might take a little while to get used to if you're a visitor to Japan, but it's an important tradition to remember when meeting people.
Interestingly, one of the only public displays of physical touch that is accepted or considered normal happens among strangers. It's not uncommon to see strangers sleeping on the shoulders of others during commutes.