ForgeCoffee
I like the idea of “Blank Hero Academy” from the USA. Maybe run by a fellow with zero presence. The only reason the faculty know he/she exists is because paperwork keeps getting filled out immaculately (and the half-hour slot scheduled in the new student welcome ceremony during which “absolutely nothing” happens).
Fun on paper but travel and amount likely to participate functionally makes it so that the kids wouldn't see home for half a year, missing the point of school. How many Schools per region? How many regions in a state/prefecture? How many of those per nation? And how many participant nations will show in the world tournament? Do note there's 206 nations at the Olympics. That's 8ish rounds of tourney brackets with just as many sets of school vs school matches. National high school sports might work for small nations, but it's impossible for big ones like China, India, and the US and actually have them attend school.