Poor, Lonely Japan

I vacationed in Japan last year, and was shocked how culturally different it felt from Korea.  The number one thing I noticed and felt strange was that everyone was alone in public and everyone was really quiet.  Everywhere I went: restaurants, coffee shops, parks, I could notice many Japanese people just walking around by themselves... alone.  I almost never see Koreans alone at a restaurant or a coffee shop.  Koreans fear being alone.