I once sparred with a GKR Black Belt 3rd Dan (note: I'm not an advanced fighter - anyone who's met me or even seen a photo of me can easily see that I'm not the most athletic person in the world) and I managed to defeat him. Turns out he wasn't wearing a cup!

But before we all start ganging up on GKR, I will say that it is an alright style to choose if you've never done any kind of martial art or sport before (and are effectively unco). GKR is pretty good at teaching you the bare basics of fighting, like stances, punching, kicking etc. GKR's basics are decent. But in my observation I find that beyond the beginner's level it's not an impressive style. I would recommend Gokanryu to someone who had no prior martial arts or sport experience and also had difficulty with coordination or the gross motor skills required to master the basic movements in martial arts. I've encountered two people who had really poor coordination and physical skills and struggled with the basics of Muay Thai and Kung Fu - and IMO they would've been better off with something simpler like GKR.

So IMHO I think GKR can be a good preliminary style for people who may be experiencing difficulty breaking into more complicated forms of martial arts... but after mastering GKR basics I'd probably recommend changing to something else.

Gokanryu is the most popular martial art in Australia. It's also an Australian style of Karate and NOT a traditional style from Japan (let alone Okinawa). I remember once visiting a Gojukai Karate Dojo in Japan and - at the time not knowing that GKR was Australian - asked them if the knew about Gokanryu. The answer was, "What's Gokanryu??"

I suspect that Kumiairyu may also be a non-traditional Australian (or Western) made style too cos I've never heard of it and I can't find any independent information about it. But I could be wrong... maybe it's just a really obscure style (like Goroquan* Kung Fu - the direct ancestor of Okinawan Karate... it's freaking hard to find any information about that style!)

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*The Chinese characters (Kanji) for Goroquan is pronounced as "Goujuuken" in Japanese; 剛柔拳 I've never seen Goroquan IRL, never seen any videos -- saw one grainy black and white photo in an article once. The closest forerunner to Karate I've personally witnessed is Wuzuquan (Five Ancestors Fist); also a Fujian style of Kung Fu like Goroquan, but _much_ easier to find! One distinguishing characteristic of Fujian Kung Fu is the "Sam Chiem" (三戦) stance and form, which of course is called "Sanchin" by the Okinawans.