Go to any sumo tournament and the first thing you'll notice is the array of giant colorful flags on bamboo poles in front of the stadium.

Known as nobori, the flags are 5.4 meters tall and 90 cm wide. They contain the name of both a wrestler (upper section) and sponsor (lower section).

While nobori have few specific rules governing their design, generally wrestlers names aren't written in black, as that color denotes a loss in sumo. Red is normally avoided for the sponsor name because, just as in English, being "in the red" isn't a place any company wishes to find itself.

Among wrestlers, only those in the top two divisions get flags, and only one for each man is allowed to be hoisted at each tournament.

Individual sumo stables as well as top-ranked referees also have nobori with their names displayed on them outside the arena.

Each individual flag is hand-painted, with the outline of the characters first drawn using a traditional calligraphy brush and ink. Once completed, they are hung outside horizontally to dry in the sun.

While smaller-printed nobori are often seen outside events and used in front of shops and businesses, only the sumo association has the massive hand-painted ones. The company which makes them has an exclusive contract with the JSA and will not create similarly styled nobori for other companies or individuals.

Fans can, however, buy miniature versions of the nobori at souvenir stalls inside the venue. They are sold individually and a purpose-built wooden stand is also available, allowing you to assemble a collection of your favorite rikishi. Rather than a sponsor name, they have a picture of the wrestlers face in the lower section.