This comment claims that Sulu is not a Japanese name (technically true), but I always assumed that Gene Roddenberry intended the name to a Japanese but was just oblivious or ignorant. It certainly seems to me that Sulu conforms more to Japanese phonology than any other language or region^{[ citation needed :) ]}.

So if we ignore the issue of the name itself, what is the actual earliest evidence that Sulu is Japanese?

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This comment claims that Sulu is not a Japanese name (technically true), but I always assumed that Gene Roddenberry intended the name to be Japanese but he was just oblivious or ignorant. It certainly seems to me that Sulu conforms more to Japanese phonology than any other language or region^{[ citation needed :) ]}.

So if we ignore the issue of the name itself, what is the actual earliest evidence that Sulu is Japanese?

Related and related

This comment claims that Sulu is not a Japanese name (technically true), but I always assumed that Gene Roddenberry intended the name to a Japanese but was just oblivious or ignorant. It certainly seems to me that Sulu conforms more to Japanese phonology than any other language of region^{[ citation needed :) ]}.

So if we ignore the issue of the name itself, what is the actual earliest evidence that Sulu is Japanese?

Related and related

This comment claims that Sulu is not a Japanese name (technically true), but I always assumed that Gene Roddenberry intended the name to a Japanese but was just oblivious or ignorant. It certainly seems to me that Sulu conforms more to Japanese phonology than any other language or region^{[ citation needed :) ]}.

So if we ignore the issue of the name itself, what is the actual earliest evidence that Sulu is Japanese?

Related and related