Amane Kasai, a third-year student at Shinsen Middle School, served as student council president until episode 37. Her family runs Fruit Parlor KASAI, a fruit and cafe shop. In civilian life, she possesses long, wavy dark purple hair, typically adorned with a yellow diamond-patterned headband, and blue eyes. Her standard outfit is a buttoned white blouse featuring a purple bow collar, a long purple skirt accented with yellow trim and straps, and dark magenta Mary-Jane shoes worn with white socks. Seasonal variations see her in summer attire with ruffled collars and checkered skirts, and winter wear incorporating sweaters and gray skirts.

Brainwashed by the Bundoru Gang, Amane became the phantom thief Gentlu. This identity transformed her hair to silver, styled in pigtails, and shifted her eyes to dark red. Gentlu's costume comprised a purple top, gray skirt, black vest with bone-like buttons, black opera-length gloves, a black-and-red cape, and boots featuring silver spikes. A blue mask and black hat bearing the Bundoru Gang logo completed her disguise. Unlike her colleagues, Gentlu eschewed violence, relying on stealth and deception to steal Recipepes—small fairies embodying dishes. Increasing headaches and emotional conflict arose as Amane's suppressed consciousness resisted the brainwashing, especially when harming Recipepes.

Gentlu's arc culminated in episode 12 when Cure Precious shattered her mask during battle, fracturing Godatz's initial control. Temporarily reverting to Amane, she was recaptured and subjected to intensified brainwashing by Narcistoru, forcing her to abandon her moral code and adopt aggressive tactics. Full liberation came when the combined powers of Cures Precious, Spicy, and Yum-Yum purified an Ubauzo containing her dark heart. Rescued, Amane took a school leave to recover physically and mentally, burdened by guilt over her actions as Gentlu.

Upon returning to school, Amane grappled with self-doubt, resigning as student council president and rejecting an offer to become a Pretty Cure despite encouragement from Rosemary and peers. This refusal caused her Heart Fruits Pendant to darken temporarily. Her resolve solidified during a confrontation with Narcistoru, who was stealing citizens' memories. Embracing her desire to protect others' smiles, she accepted the pendant, transforming into Cure Finale. Her transformation employs the Heart Fruits Pendant, and her battle introduction declares, "Gentle and Gorgeous, Fully Bloomed Sweetness! Cure Finale!"

As Cure Finale, her appearance shifts dramatically: her hair turns blonde, styled in a loose ponytail secured by a konpeito-adorned band, and her eyes become bright blue, complemented by a purple tiara-like headband. Her costume includes a white-and-yellow bodice with golden crisscross lines, light purple puffy sleeves featuring gold bands, and a magenta skirt with droplet designs. Accessories consist of a gold belt, a pink-and-purple apron, and orange-and-yellow pumps. In her enhanced Party Up Style, her hair lengthens, sleeves shorten into transparent layers accented with amethyst pearls, and her apron and skirt gain additional ruffles and floral accents. Her Children's Lunch Dress movie outfit incorporates strawberry-themed decorations and a flan-shaped skirt. Primary attacks are "Finale Bouquet" and "Delicious Finale Fanfare," executed using the Creamy Fleuret weapon.

Personality-wise, Gentlu exhibited calm detachment and cunning, utilizing persuasive tactics to manipulate victims. Post-brainwashing, Amane embodies diligence, kindness, and a strong sense of justice. Lingering guilt over her actions as Gentlu fostered self-loathing and hesitancy in leadership roles. Over time, she learned to trust her friends' support, though residual darkness in her heart occasionally surfaced. Her core motivation stems from a childhood promise to the Parfait Recipepe—a fairy she befriended—to "make everyone smile like a parfait."

Key relationships shaped her development. With Cure Precious (Yui Nagomi), mutual concern exists; Yui persistently reached out during Amane's Gentlu phase, and Amane later guided Yui on table manners. She respects Cure Spicy (Kokone Fuwa), who helped her understand consideration. Her dynamic with Cure Yum-Yum (Ran Hanamichi) involved initial exploitation—Gentlu used Ran's social media to track Recipepes—evolving into collaborative efforts to improve Ran's etiquette. The Parfait Recipepe symbolizes her childhood idealism; after rejecting its initial post-redemption partnership offer due to guilt, she reconciled and deepened their bond post-transformation. Among Bundoru Gang members, she endured Secretoru's frustration and Narcistoru's manipulative cruelty but ultimately forgave both after their betrayals by Godatz. Family bonds include her older brothers, Yuan and Mitsuki Kasai, whom she cares for despite occasional embarrassment at their affection. She shares a friendly, teasing rapport with schoolmate Takumi Shinada, aware of his crush on Yui.

Etymologically, "Gentlu" blends "gentle" and "to steal" (取る). Her surname "Kasai" combines "菓" (confectionery/fruit) and "彩" (coloring), reflecting her parfait motif. "Amane" carries meanings like "heavenly sound" or "sound of rain." "Cure Finale" signifies both the dessert course concluding a meal and the culminating act of a performance.