Depending on the branch, certain age groups are coming to specific locations but most people are students or office workers. However it is not as there are other apps created in Japan that are more user friendly and convenient to its base. In some places the staffs at the shops will purposely seat you next to a group of guys or girls to allow you to potentially have a chance to communicate. As not to embarrass anybody, they are very good at not letting on the real reason of the exchange.
If your noticing a pattern here about dating culture in Japan then your right, it is the gentlemen approach. All they have to do is talk to the customers, which are the guys. He takes it to the bustling streets of Shibuya where thousands of people cross everyday. In Tokyo there are many places where you can go try and sweet talk to a girl and get her number such as yokochos food alleys , Ginza, Shibuya, and many more places. Usually you see street nampa often at night or during a nightlife bar hopping event but this one man's approach takes it to whole new level.