So King Arthur in Japan is just English flavored Joan of Arc.
Lot of gender bent in the fate series. Basically she’s a woman that pretended to be a young looking man though Merlins magic and emotionally didn’t felt like a king which led to issues with her reign. If interested, start with fate zero there but it is a rabbit hole.
Mordred is also a woman with two mothers there, conceived with the help of some magic.
Fate was a rabbit hole that I still haven’t found the bottom of. I had trouble finding a proper watch order.
Tbf, thats very similar our pantomimes.
Relevant and recent smbc https://www.smbc-comics.com/comic/arthur
Any one interested in a meta fictional look at The Matter of Britain should read the comic series Once and Future. It’s simply superb
One of King Charles’s names is Arthur.
Amazing, do you have a link to the OP?