I spent a day at the end of September at a sumo tournament. There was a fifteen day sumo tournament in Tokyo (there are six tournaments a year, with three of them in Tokyo), and I went on the second last day. It’s possible to buy “day of” tickets to sumo tournments, but you have to arrive early. When I arrived at 8 am (when the tickets go on sale) there was already a line of over 100 people.
I’d recommend a sumo tournamet as a nearly perfect tourist activity. It’s not overly expensive (¥2100), it feels authentically Japanese, they are very well equipped to deal with tourists (they have information booklets in English and most of the staff speak very good English), there’s very little commercialization (no Coca-Cola banners hanging from the ceiling), and the rules are very simple (bouts are won when one competitor forces the other to the floor or out of the ring).
The sumo wrestlers really are huge. The match referees sit quite close to the ring, and often have to leap out of the way when one of the wrestlers is thrown out of the ring and off the dohyo. In one match, a wrestler was thrown from the dohyo and injured – it tooks several men to get him back on his feets and help him out of the arena. The day starts with amateur matches, and then in the afternoon the professional bouts begin. In the lower level amateur matches it is always the bigger wrestler that wins, but as the wrestlers become more experienced the bouts become a little more subtle in the display of skills. Right now, the two best sumo wrestlers are Mongolian, which is an embarrassment of sorts for the Japanese, but there is no doubt that they are completely dominant. In the bouts that I saw them in there was never any suggestion that they would lose.