It was not only a sport, it was a Shinto ritual that symbolized humanity's triumph over an invasion of evil spirits.
Some purists still insist on heft, but nowadays muscles will do just as well.
There are over 600 professional sumo wrestlers in Japan, divided into six divisions, with the top, the yokozuna, becoming superstars.
There are 6 Grand Sumo Tournaments every year, plus dozens of smaller tournaments, exhibitions, and competitions.
The sport has also become popular elsewhere. In the United States, sumo wrestling is offered as a sport in dozens of high schools and colleges. There are exhibitions in Japanese festivals, sports festivals, and even film festivals, as well as the U.S Sumo Open, held every year since 2001.
Maybe -- lower-level sumotori live in dormitories during their training regiment, and spend a lot of time hugging each other. Sounds like it's tailor-made for homoerotic hijinks.