Sumo rules: What you need to know

Two large men in nappies enter the ring. Seconds later, one of them is on the floor and the other is stepping back with only the vaguest look of self-satisfaction on his face. What just happened? Here's what you need to know.

Ring around

A sumo bout takes place in a ring, raised about 75 cm off the ground, approximately 4.5 metres in diametre. The hallowed ground that supports the ring is clay with a sand surface, while the ring itself is wound straw, about 8 cm in height. Traditionally, women are forbidden from even touching the setup, so - ladies - keep your inquisitive hands to yourselves.

Wrestling rules

The wrestlers crouch at their starting lines and the fight begins when all four fists (two on each wrestler, naturally) touch the ground. The fight is judged by five officials, each of them former wrestlers, and a referee. Only the ref is allowed inside the ring with the big men. The fight is decided when the loser allows any single part of his body, other than the soles of his feet, to touch the ground, or if he is forced out of the ring by the victor. The ref awards the win, but the judges can intervene in closely fought matches.

Below the belt

Forbidden moves in sumo include hair pulling, chocking, ear abuse, punching with closed fists, or crotch grabbing. Other than that, pretty much anything goes.

Moving on up

A win is also accompanied by an announcement explaining which wrestling technique was used to secure victory. In this way, wrestlers develop a reputation for certain moves and skills. Wrestlers score single points per win in the tournament, with the tournament's champion having scored the most. Wrestlers from the top two divisions wrestle everyday of each 15-day tournament, and if two are tied on 15 points by the end, a playoff decides the winner. A wrestler can only move rank by winning (or losing) the majority of his fights.

Back to Tokyo sumo tournament: the Hatsu Basho in brief