Not many athletic disciplines can keep viewers enthralled through 45 minutes of tradition before the opening contest is even determined.
Yet the detailed ceremonies unfolding in a compact earthen circle - largely unaltered for generations - accomplished exactly that.
This multi-day tournament at the historic concert hall features 40 of the very best rikishi showcasing a sport whose earliest records dates back to 23BC.
London's historic performance space has been utterly transformed, complete with a elaborate suspended canopy hanging above the competition area.
It is here the competitors, known as sumo professionals, perform their shiko exercises to banish dark forces, and where they strike their hands to summon the gods.
Above all this ancient ceremony, a giant, revolving LED screen - that would fit perfectly at an American basketball game - offers the crowd all the stats and replays they could want.
For an enthusiastic follower, it was a "unexpected footage" that first drew her interest a couple of years ago.
This was quickly followed by the discovery of specialized online content for training facilities, where wrestlers live and train, starting their day early to train, followed by a protein-rich meal and then an daytime sleep - all in the effort toward increasing mass.
Another couple discovered sumo through a conventional method: a visit to the country six years ago.
"We saw it as a common sightseeing event, but we actually developed passion for the sport," explains the fan.
"Subsequently, we tried to find communities, information, just to expand our knowledge about it," her partner continues.
Visiting the homeland is almost the only way to see a elite competition.
This London competition marks only the second occasion the tournament has appeared in the capital - the first time was in the early nineties.
Even going to Japan doesn't ensure of getting a seat, with the past period seeing completely booked tournaments.
For many attendees, the London tournament represents the premier chance they have seen live sumo - and it exceeds expectations.
"Watching nearby, you get a feeling of velocity and the force which you can't experience on TV," says Caspar Eliot. "Their stature is remarkable."
To succeed, one competitor needs to force his opponent off the clay or to the surface using brute strength.
The most use one of pair of techniques to achieve this, often in moments - pushing, or grappling.
Either way, the sound of the two rikishi crashing together in the first moment of the match resounds around the hall.
The positions right next to the ring are of course highly prized - but also, somewhat dangerous.
During one specific contest, a tall wrestler went plummeting into the spectators - perhaps making those in slightly cheaper seats breathe a sigh of relief.
Of course, the stature of the rikishi is one of the initial aspects most people think of when they consider the sport.
The venue's management revealed they "were required to locate and purchase additional seating which can withstand 200kg in weight."
But sumo - for all its successful competitions - is not without its difficulties behind the scenes.
Perhaps the demanding existence of a sumo wrestler doesn't look as appealing as it once might have.
Its following among young Japanese is also being threatened by alternative competitions, while Japan's decreasing numbers will not help.
Not that any of this has concerned enthusiasts in London.
"Experiencing the custom and formality that accompanies sumo is quite special," one enthusiast notes. "Currently, observing it in person, you experience being you are more involved."
For other committed supporters, the excitement "created amazing experiences" - as did interacting with the like-minded individuals.
"Emerging from a particularly focused online community and being able to observe numerous sumo fans live and being able to converse with other people who are just as into this as we are - it was completely valuable."
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