Sumou 相撲 is played in a ring called dohyou, and the wrestlers wear a sash called mawashi around their loins. Sumo includes many ritual elements, like the purification with salt.
Professional sumo tournaments have been held in the Ryougoku Kokugikan since 1909.
I once passed by there, on the way to Edo Tokyo Museum. This is the subway station.
Just outside the station:
The wrestlers, rikishi, were getting dressed outside. Out of respect, I am skipping those photos.
There are ukiyo-e depicting sumo wrestlers just at the entrance, on both sides.
The entrance fee can reach 14,300 yen. That is about 148 euro/person.
The same subway station:
One of the many things I appreciate about Japan is the interest in the inner grace more than the outside splendour.
Preserving traditions is something to strive for. They are incommensurable treasure.