Only a handful of competitions can keep viewers enthralled through 45 minutes of ceremony before the first point is even determined.
Yet the intricate traditions unfolding in a small clay ring - largely unaltered for hundreds of years - managed to do just that.
This five-day event at the historic concert hall features four dozen top-tier sumo athletes showcasing a sport whose first mention dates back to the first century BC.
London's historic performance space has been completely reimagined, complete with a massive traditional roof structure hanging above the ring.
It is here the competitors, known as rikishi, perform their shiko exercises to expel evil spirits, and where they strike their hands to summon the divine beings.
Above all this ancient ceremony, a enormous circular monitor - that appears natural at an American basketball game - offers the audience all the statistics and footage they could want.
For one dedicated fan, it was a "random video" that first caught her attention a couple of years ago.
This was rapidly enhanced by the discovery of specialized online content for sumo stables, where athletes reside and practice, starting their day early to work out, followed by a high protein stew and then an afternoon nap - all in the pursuit of gaining weight.
Different enthusiasts discovered sumo through a more traditional route: a visit to the country six years ago.
"We considered it a common sightseeing event, but we actually came to adore the sport," notes the enthusiast.
"Subsequently, we tried to find communities, information, just to deepen our understanding about it," her partner continues.
Traveling to Asia is typically the sole method to see a top-flight sumo tournament.
This current tournament marks only the second occasion the tournament has visited the city - the previous visit was in over three decades ago.
Even going to Japan doesn't ensure of securing tickets, with the past period seeing fully attended competitions.
For numerous spectators, the current event represents the premier chance they have seen live sumo - and it lives up to the hype.
"Observing directly, you get a sense of the speed and the power which you can't experience on TV," says Caspar Eliot. "Their stature is remarkable."
To succeed, one rikishi needs to move the other man off the clay or to the surface using physical force.
The most use one of two styles to achieve this, often in split seconds - thrusting, or wrestling.
Either way, the impact of the two wrestlers colliding in the initial contact of the match echoes around the auditorium.
The seats right next to the ring are of course greatly valued - but also, somewhat dangerous.
During one specific contest, a large wrestler fell into the audience - perhaps making those in more affordable locations breathe a sigh of relief.
Of course, the dimensions of the athletes is one of the primary elements most people think of when they consider the sport.
The hall's organizers revealed they "needed to find and purchase additional seating which can take up to 200kg in weight."
But sumo - for all its successful competitions - is not without its troubles behind the scenes.
Perhaps the rigorous lifestyle of a sumo wrestler doesn't look as attractive as it once might have.
Its popularity among youth in Japan is also being challenged by alternative competitions, while Japan's falling birthrate will not help.
Not that any of this has worried fans in London.
"Experiencing the tradition and practice that goes with sumo is quite special," an attendee explains. "Now, seeing it directly, you feel like you are more involved."
For other enthusiastic fans, the excitement "produced unforgettable moments" - as did encountering the fellow enthusiasts.
"Leaving a highly specialized online community and being able to see all these sumo fans in person and being able to speak to other people who are similarly enthusiastic as we are - it was completely valuable."
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