"Not only does her attitude bite, but so does her VOICE!"
-Sailor Venus at Emerald's laugh
Emerald is one of Prince Diamond's commanders in the Negamoon Family. She is vain, selfish, greedy, and jealous. She is in love with Diamond, and therefore jealous of Sailor Moon, whom he is in love with. She dislikes Rubeus. She has a horrible laugh. Her name is based off the gemstone, Emerald.
Emerald's first appearance was in the Episode 26, Rubeus Evens the Score, telling Rubeus that Diamond is going to kick him out. In the following episode, Emerald left Rubeus for dead on his ship as it selfdestructed, and left this part out when describing his death to Diamond.
After Diamond's droid, Grim Man, was destroyed, Emerald took over, and devised a plan to use Dark Wedges provided by Sapphire to pour dark energy into the vulnerable spots of Tokyo in order to take it over. Each of her plans was foiled, and her droids, Marzipan, Regalia, Injector, Animal Instinct, Mistrust, Doom, and Gloom were destroyed. Emerald became enraged after the deaths of Doom and Gloom, and attempted to attack the Sailor Scouts, but Diamond told her to return to the future.
When the Sailor Scouts, Tuxedo Mask, Luna, Artemis, and Rini entered the time warp to go to the future, Emerald separated them all and sent a droid named Genie of the Time Warp to capture Rini and eliminate the Sailor Scouts (deliberately leaving out Diamond's order to take Sailor Moon alive, as she was jealous of Sailor Moon and wanted her dead). This failed, as the Sailor Scouts used Sailor Planet Attack to destroy Genie of the Time Warp.
When Diamond took Sailor Moon and tried to hypnotize her into loving him, Tuxedo Mask came to rescue her. As she did not want Diamond distracted by Sailor Moon, Emerald allowed Sailor Moon and Tuxedo Mask to escape by attacking Diamond with bolts of dark energy from the shadows, unnoticed by anyone except Sapphire.
After a discussion with Sapphire on the Dark Crystal's energy reactor and how it would explode, Emerald turned to Wiseman to give her power to attack Crystal Palace. Wiseman said that she would be Diamond's queen, and gave her a crown powered by the dark crystal. Although she suspected a catch, she took it anyway. She was briefly transformed into Queen Emerald, before she was overwhelmed by its energy and was turned into a hideous dragon. She attacked Crystal Palace, stomping it, smacking it with her tail, and breathing fire at it. The Sailor Scouts came out to fight her (though Sailor Moon did not want to). All the other Sailor Scouts attacked her, but nothing they did seemed to work (though Sailor Venus and Sailor Jupiter inflicted some damage).
Remembering King Darien telling them that the dragon had a human-like mind inside, Tuxedo Mask threw a rose at her crown, which stunned her long enough for Sailor Moon to destroy her with Moon Scepter Elimination. Emerald briefly appeared in her original form before she vanished for good, falling into a dark void to her death. Restating several comments made by the Sailor Scouts in earlier episodes, Wiseman wished her good riddance, saying her laugh gave him a headache.
- Emerald is only shown to use two attacks. She can throw dark energy balls, much larger than the ones Rubeus throws, and one per fist. She tries to use this on the Sailor Scouts, but is stopped by Diamond. Her other attack is to shoot dark energy bolts similar to Rubeus, which she uses on Diamond (offscreen) to let Sailor Moon and Tuxedo Mask escape, as Diamond was trying to get her to fall in love with him, which both made her jealous and seemed to distract him from their mission to take over the world.
- In her dragon form, Emerald gains new attacks by simply by flying toward her opponents so she can knock them down. She also attacks by stomping, swinging her tail at her opponents, trying to bite or eat them alive, or breathing fire on them until they burned into ashes.
- Emerald is easily distracted by cakes, as evidenced in the episode Emerald Takes Over.
- Emerald is the first and only dragon character who ever appears in the entire Sailor Moon series.
- Her dragon transformation is similar to that of dragon Maleficent from Sleeping Beauty and Dorothy the Dragon Ghost from Danny Phantom series.
- Of all the characters from the future, Emerald is the only one to die in the future, as Rubeus, Sapphire, Diamond, and Wiseman all die in the present
- Emerald is one of three Sailor Moon R villains to not reform, other two being Rubeus and Wiseman.