Summer is full of festivals. 盆踊り (Bon Odori) is one of them. Each place has their own version of this with their own dances and songs. This one was in 下北沢 (Shimokitazawa) in 東京 (Tōkyō). It was a very casual family gathering. The people on the platforms would teach the crowd how to do the dances and then everyone would participate.