Well, current japan, especially in big cities, is more tolerant to the affection of love, with the exception of older generation in the 40s usually. Showing affection like holding hand/arm, hugging, kissing to cheek, etc are usually tolerated in public places.
Kissing or even french kissing (in public places) on the other hand, unfortunately are still viewed as an uncouth and uncommon thing (as most asian countries do). Well, in the end, as the society progress (with japanese people are more tolerant to the western culture), I guess in time kissing will be commonly accepted