Mahiro here is practicing the Kankudai (or Kanku Dai depending on which hastily-googled page you're looking at), one of the more advanced routines in karate.
Look at 'em go! Little Van Damme's, the whole lot of them! And we even have them in GIF form thanks to the folks at I Hate My Parents:
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This is Going Too Far: Twitch Gamer Gets "Swatted"
It's Me! It's You!
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Don't Stare too Long at This Ring Dance, You'll Get Hypnotized
This Les Mis Flash Mob is Probably the Lamest Flash Mob Ever
Make it All Count!
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Attack on Titan Meets Pokémon and I'm Never Sleeping Again
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