When I was in Japan recently, one of the many fascinating things I found was pachinko. Pachinko is described to be like a vertical pinball machine. I saw pachinko parlours in many places and they were quite recognisable by their loud colours and with lots of slot machines.
I had no idea about the game, but I walked into a parlour to check it out. I didn't get very far because the noise level was high... almost like a million bees buzzing at the same time! Wow, it was undescribable and unbelievable. I stayed inside for less than 10 seconds, and then left quickly.
If you visit Japan, do check them out. They are fascinating :).