I had a really great night at The Rooftop bar drinking beer and chatting to people.
It is a very nice bar, you pay per hour and you drink as much as you want in that time, which works out to be a really good system. The bar attracts a lot of young and even slightly older Japanese people and westerners, I met Japanese people ranging from their 20's to 50's. Everyone in the bar immediately chats to each other and greets them upon entry, it feels like one big party, which is rare in many bars. An excellent place to make friends.
It was so much fun that we went back again the second night, and so did a few of the other customers.