This page contains information regarding Star Trek: Lower Decks, and thus may contain spoilers.
The Risians or Risans were a humanoid species native to the Federation planet Risa. They resembled Humans save for a small button-like decoration on their foreheads. They also differed internally, such as that in the 2150s a Risian hospital would have difficulty treating a Human. (DS9: "Let He Who Is Without Sin..."; ENT: "Two Days and Two Nights")
Centuries ago, the Risians tamed the earthquakes and rainstorms of their homeworld by installing seismic regulators and a weather control system. By the mid-22nd century, Risa had become well-known as a cosmopolitan vacation destination. (DS9: "Let He Who Is Without Sin..."; ENT: "Two Days and Two Nights")
The Risians were known for their sexually permissive culture. The horga'hn, a Risian fertility symbol, was omnipresent in Risian culture. Any individual who displayed a horga'hn statuette indicated their receptiveness to jamaharon, a mysterious and pleasurable sexual practice. Risian women were described as "imaginative" by William Riker in 2366 and as "voluptuous" by Zek in 2369.(TNG: "Captain's Holiday"; DS9: "The Nagus", "Let He Who Is Without Sin...")