A sumo match is called a tori-kumi. In principle only sumo wrestlers who belong to different stables compete against each other. From the moment the rikishi are called to the dohyo until they withdraw you will see all kinds of rituals and conventions. If you know a little about their origin and meaning you will find the bouts more interesting.
Entrance
Rikishi enter the stadium about 2 matches before
their own, and wait their turn in a special place
near the dohyo. Those who have at least the rank
of juryo wait seated on their own special zabuton
cushion.
The Yobidashi (Announcer)
When one bout ends, wooden clappers (hyoshi-gi)
announce the next. At this signal the next pair
of rikishi stands up. The yobidashi (announcer)
holds his white fan at eye level and reads out the
names in a theatrical voice. The rikishi mounts
the dohyo when his name is called.
Shiko (Ritual
Stamping)
With one leg bent at the knee, the rikishi
raises his other leg, then brings it down
hard. This stamping, called shiko, is an important
ritual in sumo. It strengthens the lower body,
and is a warm-up exercise as well. Shiko also
shows the rikishi's eagerness to trample on
his opponent and to crush any evil that may
lurk underneath.
Sonkyo
Sonkyo is a crouching posture signifying respect
for one's rival. Hands are placed on the knees,
which are far apart, the buttocks rest on
the heels, and shoulder muscles are relaxed.
The aim here is to steady the nerves and breathing.
Chiri-chozu
Next the wrestlers conduct a ritual with their
hands. They put both hands together, then
spread them apart in a small circular motion
with their palms up, point them downwards,
then move them back to the original position.
This polite gesture indicates the rikishi
are concealing no weapon, and that they are
ready to fight fair and square.
Kiyome-jio Before the bout the rikishi throw salt
on the dohyo. In Japan since ancient times
salt has been regarded as a purifier. The
salt in sumo cleanses the dohyo, and symbolizes
the wish to avoid injury. It also kills germs
and helps to harden the dirt.
Chikara-mizu
("water of strength")
On the dohyo the wrestlers receive water brought
in a ladle by the rikishi who won the previous
bout, or by one who is waiting. This water
is used to rinse the mouth, and helps to concentrate
one's energy. Next the lips are wiped dry
with chikara-gami ("paper of strength")
-- this symbolizes a cleansing of the body.
Prize Money Pennants
Different companies and associations offer prize
money which will go to the winner (the amount of
each prize is fixed). Before the match the announcer
makes one turn around the dohyo with pennants which
display the sponsors' names. If the rikishi is popular,
and before much-awaited bouts, many prizes are offered,
and the crowd rumbles in anticipation.
相撲１〜力士の土俵入りから清め塩まで〜 
