Few sports can hold spectators spellbound through 45 minutes of ritual before the initial score is even contested.
Yet the complex rituals unfolding in a traditional dohyō - largely unaltered for centuries - accomplished exactly that.
This five-day event at the historic concert hall features numerous elite sumo wrestlers showcasing a sport whose initial documentation dates back to the first century BC.
London's historic performance space has been totally redesigned, complete with a elaborate suspended canopy hanging above the competition area.
It is here the wrestlers, known as rikishi, perform their foot stomping to expel negative energies, and where they clap to summon the gods.
Above all this historical practice, a enormous circular monitor - that would fit perfectly at an American basketball game - offers the audience all the data and video they could want.
For Sian Spencer, it was a "random video" that first caught her attention a couple of years ago.
This was quickly followed by the discovery of dedicated YouTube channels for rikishi houses, 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 effort toward bulking up.
Different enthusiasts discovered sumo through a more traditional route: a visit to the country six years ago.
"We approached it as a very touristy activity, but we actually developed passion for the sport," notes the enthusiast.
"From there on, we tried to find communities, information, just to expand our knowledge about it," the other fan explains.
Visiting the homeland is almost the only way to see a major championship.
This London competition marks only the second time the tournament has visited the city - the previous visit was in 1991.
Even going to Japan doesn't ensure of securing tickets, with current times seeing sold-out events.
For multiple fans, the current event represents the first time they have experienced the sport directly - and it lives up to the hype.
"Observing directly, you get a understanding of quickness and the force which you don't get on TV," explains an attendee. "Their size is impressive."
To win the match, one competitor needs to move the other man off the clay or to the floor using brute strength.
The majority use one of two styles to succeed in this, often in instantaneous actions - pushing, or clenching.
Either way, the noise of the two athletes meeting in the first moment of the match reverberates around the venue.
The seats right next to the dohyō are of course extremely sought-after - but also, somewhat dangerous.
During one specific contest, a large wrestler tumbled into the crowd - perhaps making those in less expensive positions breathe a sigh of relief.
Of course, the size of the wrestlers is one of the primary elements most people think of when they think of sumo.
The hall's organizers revealed they "needed to find and purchase additional seating which can support 200kg in weight."
But sumo - for all its successful competitions - is not without its troubles behind the scenes.
Perhaps the demanding existence of a rikishi doesn't look as desirable as it once might have.
Its popularity among young Japanese is also being challenged by other sports, while Japan's declining population will create further complications.
Not that any of this has concerned enthusiasts in London.
"Seeing all this tradition and practice that is part of sumo is particularly meaningful," fan Sian says. "Currently, observing it in person, you experience being you are more involved."
For other dedicated followers, the intensity "made it so incredible" - as did encountering the other fans.
"Getting out of a very niche online community and being able to see all these sumo fans directly and being able to chat with other people who are just as into this as we are - it was worth every penny."
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