One of the defining sights of a sumo tournament is the parade of brightly colored kensho banners around the ring before the highest- ranked wrestlers fight.

While many bouts in the top division have three to five banners, those involving the most popular wrestlers such as the yokozuna can reach up to 50 or more.

The banners represent prize money staked on that bout by corporate sponsors. Each one costs ¥62,000 with ¥56,700 going to the winner of the match and ¥5,300 deducted for costs and fees.

Half the money is given to the winner by the gyoji (referee) on the ring immediately following the fight, and the rest is put in a special fund to be paid upon retirement to the wrestler in question.

In principle a sponsor has to pay for at least one banner for each day of a tournament.

Banners may only be paid for by companies not individuals, but longtime sumo fan Paul McCartney got around this restriction five years ago when he used the kensho banners to advertise his new album.

The name of each banner is read out over the public address system in the arena as they are carried around the ring.

If you are watching sumo on TV at that time, you will notice the camera zoom out and the background noise become muted.

This is because NHK (Japan's public broadcaster) is funded by a license fee and not allowed to run advertisements. The organization as a result is zealous about avoiding any mention of company names or showing their logos.

When a wrestler defeats a yokozuna and gets a large amount of kensho, he often uses it to treat the lower-ranked grapplers in his stable by taking them out to dinner at a nice restaurant and footing the bill.