“Risa” was an invention entirely of the “Next Generation” and subsequent series. It had never been mentioned on The Original Series (TOS).
In contrast, the planet to which you are referring was from the TOS episode “Shore Leave.” It was referred to in the episode only as “an uninhabited planet in the Omicron Delta region.”
Regards
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Is that you Sheldon?
No, just someone capable of spending 15 seconds to google "McCoy" and "two showgirls."
Regards,