@Nylodale Probably. I'm not Japanese, so can't say for sure, but I'm Asian, and in many Asian countries, too much skinship is a "taboo" of some sort. When I say "taboo" here, I don't mean that you'll be a social pariah or anything for doing it, but more like unusual. People are usually too embarassed to kiss in public. The most a couple would do is hold hands. If there's a kiss, it's almost always a quick peck, instead of a deep kiss.
Asian cultures are just more reserved in general, when it comes to things like these.