Sumo is an act of God and a festival in the Japanese ancient times when a sumo wrestler takes the form that an association fights on a sumo ring and it is also military/martial arts.
The Grand Sumo Tournament has been carried out as performance for a long time.
In late years it is performed as the military/martial arts or sports derived from Japan globally.
Sumo is Shinto ritual based on the Shinto which is religion peculiar to Japan, and manners are made much of because it is done with respect and the act indicating thanks by gods, and the sumo wrestler does not wear it other than a mawashi as the part.
The regular sumo tournament is held six times a year in an odd month, and the three times of those are held at the Kokugikan of Tokyo, and other three times are held each at Osaka, Fukuoka, Nagoya for 15 days.
If you have a chance to visit to Japan on the season of the Sumo tournament, we recommend you to watch sumo as a game of the national sport of Japan.
You will be able to enjoy the tournament all day at the place.