Towa Akagi, originally Princess Hope Delight Towa, is the younger sister of Prince Kanata and a princess of the Hope Kingdom. As a child, she aspired to become a Grand Princess, aware only a Princess Pretty Cure could attain this. Dyspear exploited this desire, luring her into the Forest of Despair with false promises. Towa was brainwashed and transformed into Twilight, the "Princess of Despair," believing Dyspear was her mother. Twilight dismissed dreams as illusions, viewed the Pretty Cures as impostors, and exhibited ruthless, vain behavior, declaring herself "Noble, Precious, and Beauteous." She wielded blue flames and used three Dark Dress-Up Keys: one to empower Zetsuborgs, another to summon a staff for trapping people in mirrors, and a third to transform into the Black Princess, a dark Pretty Cure counterpart that caused her physical deterioration.

After a confrontation with the Pretty Cures, especially Cure Flora (Haruka Haruka), and hearing Kanata's violin, Towa broke free from Dyspear's control. She reverted to her true self but retained fragmented memories of being Twilight. Post-purification, Towa displayed social awkwardness and naivety stemming from her royal upbringing and isolation, struggling with Earth customs like attempting to purchase a castle and servants. Her core personality remained kind, courageous, and observant, with heightened perceptiveness due to Dyspear's betrayal. She deeply admired Kanata and formed close bonds with her fellow Pretty Cures, particularly after Kirara Amanogawa became her roommate and Minami Kaido helped her overcome a fear of darkness, a remnant of her trauma.

Towa became Cure Scarlet, the Princess of Crimson Flames, wielding fire-based powers. Her transformation altered her appearance: light-red hair turned pink with magenta ombre, she gained feathery wings behind her ears, a gold tiara with ruby gems, and a ruffled white dress accented with red feathers and gold details. Her weapon, the Scarlet Violin, enabled attacks like "Scarlet Flame" and "Scarlet Spark." Using Dress-Up Keys for Mode Elegant forms: Phoenix allowed "Phoenix Blaze," Sun facilitated group attacks like "Éclat Espoir," and Royal granted flight for "Grand Printemps." Her Grand Princess form added a golden cape and enhanced abilities.

In "Go! Princess Pretty Cure the Movie," Towa played a significant role in "The Pumpkin Kingdom's Treasure." Transported to the Pumpkin Kingdom during a Zetsuborg attack, she grew suspicious of Minister Warp during a Princess Convention. Participating in contests, she uncovered Warp's manipulation of the king and queen and the forced labor of pumpkin fairies. Her vigilance exposed Warp's plot to capture the Pretty Cures, leading to the group using Miracle Princess Light to defeat him and restore the kingdom. Later, in "Leff's Wonder Night!," she aided Princess Leff against Night Pumpkin, helping restore light to the Night Kingdom.

Towa's design includes distinctive elf-like ears. As Twilight, she wore a silver hairstyle with a bow-shaped bun, red makeup, and a dark grey mini-dress with wing accents. As Cure Scarlet, her Mode Elegant forms featured elaborate gowns: Phoenix had a floor-length skirt with maroon peplum, Sun had a white dress with apricot ribbons. Her casual attire included a white dress with pink details or a school uniform with a blue blouse and white skirt.

Her name reflects her journey: "Towa" derives from "twilight" (トワイライト), symbolizing despair and rebirth, while "Akagi" combines "red" (紅) and "castle" (城), referencing her theme color and royal status. "Cure Scarlet" denotes her bright red-orange flame powers. Personal details include her birthday (December 15), Sagittarius zodiac sign, fear of spiders, and hobby of playing the violin, a skill shared with Kanata.

In adulthood, Towa became queen of the Hope Kingdom, wearing regal white-and-red gowns and a jeweled tiara, fulfilling her childhood dream.