Flower Knight Purity is the alter ego of a young girl named Lily Kazahana, a character from the anime Princession Orchestra. Lily is a ten-year-old student in the fifth grade, known for her quiet and reserved nature. Unlike many children her age, she rarely displays her emotions openly and tends to speak in a mature, adult-like tone. Her physical appearance includes lavender hair styled into long, low pigtails and dark lilac eyes. As a civilian, her image color is associated with white. The name Lily references the flower, and her knight name, Purity, directly corresponds to the flower language often attributed to lilies.

The background of Flower Knight Purity is deeply connected to the fantasy world of Alicepia and its hidden dangers. Prior to becoming a knight, Lily experienced the sudden disappearance of a close friend named Toma. The White Queen, a powerful and mysterious figure, later revealed the painful truth to Lily: Toma did not vanish without cause but was destroyed because the ever-growing musical power of Alicepia became too potent and poisonous for him to survive. This traumatic event and revelation motivated Lily to take action. She accepted the White Queen's offer to become a Flower Knight, adopting the name Purity. Her primary motivation is to prevent any other resident of Alicepia from suffering the same fate as Toma. She believes that by fighting as a Flower Knight, she can help control and seal away excessive musical power, thus preserving the fragile peace of the world and protecting its inhabitants.

Within the story, Flower Knight Purity serves as a secondary antagonist for a significant period, acting under the command of the White Queen. Her role is to oppose the main protagonists, the Princesses, by extracting and sealing musical energy. She fights alongside another Flower Knight named Sincere, who is later revealed to be her older sister, Sumire Kazahana. Purity is a formidable opponent, utilizing speed and skill in combat. She is shown to wield both a long sword and a short sword simultaneously, employing a versatile fighting style that can pressure the Princesses. She also possesses other abilities common to Flower Knights, such as teleportation and the power to summon and command creatures known as Jammerwocks to absorb musical essence. The key relationship in her life is with her sister Sumire, who is fiercely protective of her and tries to save her from her self-destructive path. Another significant, though tragic, relationship is her bond with the memory of her lost friend, Toma, whose fate continues to drive her actions.

The most crucial development for Flower Knight Purity occurs when her sister Sumire confronts her. Overwhelmed by guilt over Toma's disappearance, Purity becomes consumed by her mission and nearly loses control. It is only through Sumire's sincere and heartfelt words that Lily is able to finally express her true feelings, admitting that she never wanted to be separated from Toma. This emotional breakthrough causes her to lose her powers as a Flower Knight, as the White Queen revokes them. However, this loss leads to a rebirth. Having faced her grief and accepted her sister's love, Lily gains a new, more powerful form, awakening as a Princess herself, with the transformation name of Princess Neige, which means snow in French. This marks her transition from an antagonist guided by sorrow to an ally fighting with hope. As Princess Neige, her appearance changes dramatically; her hair grows longer, her eyes brighten, and she dons a white dress adorned with flower and bell motifs, representing her purified and empowered state. As a notable ability in her final form, she can access an enhanced state called the Circle of Life form, further amplifying her power.