May be a stretch, since I can't imagine many western speedrunners are fans of sumo as well, but the best (and most authentic) sumo game out there recently got an official leaderboard and discord.
We'd like to invite any sumo fan, any wrestling fan, any fighting game speedrunners - heck, just anyone who is interested - to come check out the game. If it seems too confusing, don't worry; we'll happily answer questions in the discord, and guides are being put out soon.
Should also mention that it's a relatively short run. Top times are under 15 minutes, and even if you're just starting out, it's likely your first runs won't clock in above 20 minutes. So for anyone interested in running a shorter game with tons of categories and subcategories to conquer, this could be your game.