After Jedite was defeated by the Sailor Scouts and put into Eternal Sleep by Queen Beryl, Neflite became the new commander. He did not get along with Zoycite at all, with Zoycite hoping that he would fail and be punished.
His strategies revolved around draining more energy from one person than Jedite could have taken from several people at once. He would find out whose energy was about to reach its highest peak, then implant a Negamonster's essence inside an object close to that person. This would turn the person evil. Once the energy reached its highest point, then the monster would come out of the item and start draining energy, but Sailor Moon foiled all of his plans, destroying the monsters, which consisted of Tensie, Petasos, Black Widow, Kyameran, and Jumo.
At one point, he attempted to use Tuxedo Mask as Sailor Moon's weakness to destroy her, sending Leo the Lion to attack them. He was unable to destroy her, but was not punished by Queen Beryl, as he was able to steal energy from Molly for the Negaforce. Molly fell in love with him before this, and he erased her memory of the attack afterwards.
Afterward, Beryl began looking for the Moon Princess. Neflite assumed that Princess Diamond was the Moon Princess, and implanted Soul Shadow in her, but Soul Shadow was driven out of her, and Sailor Moon destroyed him.
Molly was still in love with Neflite even after learning that he was evil, and protected him from Sailor Moon's tiara after he was defeated by the Sailor Scouts. When Zoycite's monster Yasha attacked, Neflite protected Molly from her attack, much to his shock. Yasha was destroyed by Sailor Moon.
Neflite told Molly he wanted to fight alongside the Sailor Scouts against the Negaverse, and asked her who Sailor Moon was. Molly didn't know, and called Serena. From this, Neflite assumed that Serena was Sailor Moon, and was proven right when he saw her transform. He attacked her, but Tuxedo Mask arrived. Then Neflite sensed that Molly was in danger, as three of Zoycite's monsters - Housenka, Grape, and Suzuran - kidnapped her. Neflite went to save her, beating up the monsters. However, the monsters found them again, and Housenka stabbed Neflite with thorns from her arm. The Sailor Scouts arrived and killed the monsters.
Neflite died of his injuries, and dissolved into dust, leaving only the bandage Molly put on his arm from a cut he received earler.
Neflite can create a sword to attack his enemies. He can also shoot an energy beam called the Starlight Attack.