As with boxing, wrestling, MMA or any other activity where two contestants face off in a ring, great rivalries are the lifeblood of Japan's national sport.
While it's true that sumo is a lifestyle more than a sport, and its day-to-day practices and rituals are equally (if not more) important than results in the ring, the sport's wider popularity has always been driven by rivalries at the top.
That's something that is clearly reflected in publishers and media organization's endless production of magazines and DVDs focusing on the great battles of the past.