I think you might have taken the shot on January 14 - it is the Coming of the Age Day, which is still 20 years old in Japan. Now they are discussing in the Diet a change to 18 years old for being declared an adult. On this day most people of 20 get dressed in colourful kimonos (both women and men) and participate in official celebrations for the occasion. You probably happen to be at a crossroads where these young people were headed for the celebratory hall.