Darknest is the main antagonist of Star☆Twinkle Pretty Cure and the leader of the Notraiders. Constantly concealing her true appearance and voice, her identity wasn't revealed until episode 46. Darknest is actually the Ophiuchus Star Princess, one of the Star Princesses that created the universe.
She was voiced by Mie Sonozaki.
Darknest appears as a tall humanoid being wearing a full-body armor and long cape. Their snake-like features are based on the Japanese yokai Uwabami, although they were also a hint to their true idenitty. Darknest's face is hidden in the shadows of her helment, and her voice is distorted to hide the fact that she is actually a woman and one of the Star Princesses.
As the Ophiuchus Star Princess, she is an elegant adult female like other Star Princesses. The Ophiuchus Star Princess has long wavy emerald green hair that reaches her feet, held up in several purple bands with two long crimson strands in the front. Her eyes are bright yellow with green pupils. Like the other Star Princesses, her pupils have stars on them.
She wears a sleeveless dress with dark indigo and light purple bodice that is lined with gold at the top along with a feathery purple collar. The skirt is floor-length and purple with a dark indigo layer over it. Along the middle is a white section decorated with light purple oval-like designs and an indigo border.
Her accessories include a gold halo-like tiara that resembles a snake, a gold choker, gold crescent-shaped earrings, a wrap around her arms that resembles a bright green snake, and two gold bands on her upper arms. She later takes Garuouga's bracelet.
As Darknest, she appears very serious and power hungry, and desperately wants the power of the Star Princesses and Fuwa for her own purposes. She also neglects their minions' well-being and regards them as pawns.
After dropping her disguise, the Ophiuchus Star Princess acts more haughty and femenine and teases the other Star Princesses about their failures. She distrusts mortals and believes they didn't deserve the gift of imagination as it will only lead them to destroy the current universe.
As Darknest she has the ability to power up the Notraiders and can also produce holographic projections. After outing herself as the Ophichus Star Princess she reveals that she has the ability to control black holes.
- Garuouga - The former second-in-command in the organization. She manipulated him by destroying his planet.
- Kappard, Tenjo, and Aiwarn - Darknest's former subordinates.
- Star Princesses - The Ophichus Star Princess was once part of their group, but she abandoned them after becoming delusioned with the current universe. She wants to use their power to destroy the universe and start anew.
In the beginning of history, the thirteen Star Princesses created the universe and protected its existance from the Star Palace. However, the other Star Princesses decided to give the gift of imagination to mortals. The Ophiuchus Star Princess disagreed, believing that it would only lead to mortals becoming distorted and driving the universe to its eventual destruction. With their combined powers, the other Star Princesses defeated the Ophiuchus Star Princess and banished her from the Star Palace.
The Ophiuchus Star Princess hid in the depths of the darkness to gather her power, eating planets to regain her strength. She began plotting to use the power of Fuwa, who she refers to as "the vessel", and her fellow Star Princesses to complete a ritual that destroy the universe and create a new one according to her will. She disguised herself as Darknest and began recruiting twisted individuals into the Notraiders, who she fooled by telling them she merely wanted to take over the universe.
- Darknest's background and identity as a Princess is hidden by their full-body armor and a voice distorter that disguises her gender, making her sound deep and masculine.