One of most popular sports in Japan, sumo is also a ritual and colorful piece of of theater.
The origins of sumo go back to a myth: Takemikazuchi-no-kami and Takeminakata-no-kami, two gods, fighting over the rule of the country.
Sumo is also related to an old Shinto ritual: boys wrestling in order to predict if weather and crops would be good in a given year.
There are no weight restrictions or classes in Japanese sumo, so wrestlers are often matched off against someone many times their size. Therefore, weight gain is an essential part of sumo training.
But it's not just the weight of sumo wrestlers that is admired, even more important are technique and composure.
Japanese wrestlers are also supposed to look feminine, with no bodily hair. In Shinto religion hair was considered impure. The image of hairless plump wrestler overlaps with that of the "pregnant earth-mother" symbolic of a good harvest.
Some pre-match rituals - sprinkling of salt over the ring for purification, for example - also have their roots in the religious origins of the sport.
In line with tradition, only men practice the sport professionally in Japan. However, women are avid watchers and make sure ancient traditions are sustained.
Supposedly, during important tournaments, Japanese parents (tiger moms?) force their children to watch sumo on TV.