Juliet, whose full name is Juliet Fiammata Arst de Capulet, is the central protagonist of the series. She is the last surviving member of the House of Capulet, the family that once ruled the floating city of Neo Verona before being overthrown and massacred by the Montagues fourteen years prior to the main story. As a very young child, she was the sole member of her family to escape the slaughter, rescued by the loyal family retainers who then raised her in hiding. To protect her from the usurping House of Montague, which continues to search for any surviving Capulet heirs, Juliet is forced to conceal her true identity. She does this by living disguised as a boy named Odin, a practice that has shaped much of her early life.

In terms of personality, Juliet is depicted as a strong, intelligent, and compassionate young woman with a deeply ingrained sense of justice. Unlike the sheltered and naive girl of the original play, this version of Juliet is proactive and resourceful. She chafes at the restrictions of living in disguise but bears a quiet determination to help others. This drive leads her to adopt a second secret identity as the Red Whirlwind, a masked vigilante who fights to protect the common people of Neo Verona from the oppression and cruelty of the ruling Montague regime. As the Red Whirlwind, she becomes a symbol of hope for the citizenry and a thorn in the side of the tyrannical Lord Montague. Though she is fierce in combat and dedicated to her cause, she is also deeply loving and struggles with the violent legacy of her family name, showing strong qualms about killing and a desire to end the conflict without further bloodshed.

Juliets central motivation evolves throughout the story. Initially, she is unaware of her true heritage and simply wishes to use her skills as the Red Whirlwind to aid those in need. Upon learning the truth of her familys murder on her sixteenth birthday, she feels a heavy sense of duty and responsibility to restore the Capulet name and liberate Neo Verona from Montagues tyranny. This sense of obligation quickly becomes complicated when she meets and falls in love with Romeo, the kind-hearted son of her familys mortal enemy. Her primary internal conflict stems from being torn between her profound love for Romeo and her duty as the last Capulet to lead the rebellion against his family. Her motivation shifts towards finding a way to reconcile these two opposing forces and create a peaceful future, even as a darker destiny tied to the magical Great Tree Escalus begins to call to her.

In the story, Juliet serves as the driving focus. While the romance is central, she is the leader of the Capulet Restoration movement and the active agent of change against the Montague dictatorship. Her role involves rallying the people, engaging in direct combat, and making difficult decisions for the greater good. Her key relationships are fundamental to her development. Her bond with Romeo is the emotional core, representing a forbidden love that challenges the long-standing hatred between their families. She is also deeply connected to her loyal caretakers and friends, including the childhood friend Cordelia, the devoted retainer Conrad who saved her life, and Antonio, who acts as her sidekick. A significant and complex relationship also develops with Tybalt, a mysterious and powerful warrior whose connection to the Montagues and Capulets adds further depth to her struggle.

Juliet undergoes significant development, transforming from a girl with no memory of her past into a determined leader who accepts her heritage and her destiny. Initially, she insists she has no desire for revenge, but she gradually steps into her role as the figurehead of the rebellion. Her relationship with Romeo forces her to mature, as she first pushes him away upon learning his identity before ultimately committing to him and their shared vision of a new world. Her journey culminates when she learns of the Capulet family`s dark secret: the daughters of the House of Capulet are the seeds of the Great Tree Escalus, which holds the floating city aloft. As the tree is dying, Juliet is chosen to sacrifice herself by merging with it to save Neo Verona. In the end, after Romeo is fatally wounded, she willingly makes this heroic sacrifice, holding him in her arms as she merges with the tree, descending the city safely to the ground.

Regarding her notable abilities, Juliet is an excellent and highly skilled swordswoman, a talent she develops during her years as the vigilante Red Whirlwind. Her fighting ability allows her to go toe-to-toe with trained soldiers and other skilled warriors like Tybalt. She is also a capable rider able to handle a dragon steed. Finally, she possesses a unique, almost psychic connection to the Great Tree Escalus, as the chosen "seed" of the Capulet line, which is the source of her ultimate sacrificial power.