Emiru Aisaki is a sixth-grade student at Kotori Nono's elementary school. She possesses striking red eyes and auburn hair, usually styled in twin tails fastened with red ribbons and often accompanied by a red neck bow. Her everyday outfits feature dresses blending white, pink, red, and dark gray, incorporating diamond or heart patterns, worn with mary-jane shoes and white stockings displaying red diamond motifs. For winter, she wears a red dress with puffed sleeves; formal occasions call for layered skirts and frilled socks. As an adult, her hair grows longer, slightly disheveled, and is tied with red bands, complemented by gold diamond earrings and sophisticated attire mixing dark purple jackets, zippered dresses, and heeled boots.

Emiru's personality centers on intense protectiveness towards others while resisting care directed at herself. She idolizes heroic figures and aspires to become one, sometimes taking this zeal to extremes. Despite occasional overprotectiveness, she demonstrates deep care for her friends, actively supporting and uplifting them. She harbors a passionate love for singing and playing the guitar, interests initially discouraged by her older brother, Masato, who deemed them unladylike compared to instruments like violin or piano. Childish traits persist, such as sleeping with stuffed animals and requiring evidence before accepting claims. Emotionally sensitive, this trait once led to a temporary loss of her singing voice. Her speech is characterized by ending sentences with "nano desu" for emphasis.

Her family includes parents Haidon and Miyako, grandfather Baku, and brother Masato. Early interactions with Masato involved sexist restrictions on her hobbies, though he later becomes supportive, gifting her concert tickets and encouraging her musical pursuits. Her pivotal relationship is with Ruru Amour, an android she first encounters during a self-styled "heroic" act. Their bond strengthens when Ruru defends her against Masato’s criticisms. Discovering Ruru’s android identity initially stuns her, but they form an inseparable partnership. They eventually co-found the musical duo "Twin Love," sharing guitar playing and singing. Emiru experiences profound sadness when Ruru departs for the future, though they reunite later under altered circumstances.

Emiru's journey to becoming Cure Macherie begins with admiration for the Pretty Cures after being rescued by Cure Yell. She initially adopts the self-proclaimed alias "Cure Emile," wearing a costume with pink ribbons, a hot pink skirt, and navy suspenders. Her official transformation into Cure Macherie occurs alongside Ruru (as Cure Amour) in episode 20. As Cure Macherie, she undergoes physical changes: her stature increases, her eyes brighten, and her hair transforms into platinum blonde thigh-length curled twin tails. Her costume is a lolita-style dress with puffed sleeves, layered magenta and pale pink frilled skirts, light red boots with ribbon accents, and pale pink gloves. Accessories include a large hair ribbon with pale blue frills and a gold diamond centerpiece. Advanced forms like Cheerful Style introduce rainbow-gradient ribbons, extended lace veils, and flower-petal skirt layers, while Mother Heart Style adds translucent butterfly wings.

Transforming into Cure Macherie requires the PreHeart device and her Mirai Crystal, uniquely achievable without fairy or mascot assistance when combined with Cure Amour’s power. Her attacks include "Heart Song," performed jointly with Cure Amour using their PreHearts and Mirai Crystals, and "Twin Love Rock Beat." She is designated the "Pretty Cure of Love & Singing," with her name derived from the French term of endearment "ma chérie" ("my sweetheart"). The combination of her and Cure Amour’s names forms the French phrase "ma chère amour" ("my dear love").

Key developments include overcoming her fear of tengu and sleepwalking tendencies. Her musical passion culminates in a future career as a rock singer and guitarist, performing in bands and achieving fame. In the epilogue, she reunites with a reborn Ruru who, while initially not recognizing her, recalls their shared songs, reigniting their connection. The name "Emiru" carries meanings like "seeing love" or "true love" in kanji, but within the series context signifies "smile at Ruru," reflecting their bond. Her surname "Aisaki" combines "love" (愛) and "small peninsula" (崎).

In the film "Pretty Cure Miracle Universe," she appears as part of the HUGtto! Pretty Cure team alongside Cure Yell, Cure Ange, Cure Étoile, and Cure Amour. They join forces with teams from "Kirakira Pretty Cure a la Mode" and "Star Twinkle PreCure" after being transported across planets by Piton, a Miracle Light-creating creature. The Cures combat Yango, who manipulates citizens using Dark Lights. The collective teams unite their powers to purify Yango, restoring peace.