Lala Hagoromo hails from Planet Saman, considered an adult there despite being thirteen in Earth years. She arrives on Earth fleeing Notraiders while searching for the legendary Pretty Cure alongside Prunce and Fuwa. During this mission, she meets Hikaru Hoshina and becomes Cure Milky, the Pretty Cure of the Milky Way. Her civilian look features short dark turquoise hair with pale blue and light pink streaks, pointy ears, antennae tipped with yellow orbs, and a white mini-dress paired with a bolero jacket. She carries a Saturn-inspired purse holding shooting star gummies and wears a Star Color Pendant. In winter, she adds a pale yellow jacket and turquoise cap. As a young adult, her hair grows longer, styled in twin-tails with silver accessories, and she wears a yellow beret and jacket. Transforming into Cure Milky lightens her hair color and adds star-shaped ornaments. Her Cure outfit includes a turquoise-and-yellow swirl-patterned top with bubble sleeves, cyan shorts, and gradient stockings. Special forms include Leo Cure Milky, characterized by wilder hair and a blue lion's tail, and Cancer Cure Milky, featuring short twin-tails with a green gradient and crab claw ornaments. She ends sentences with "~lun" and uses "Oyo~" as a catchphrase.

Her personality combines seriousness and a strong sense of responsibility, shaped by her family frequently highlighting her flaws rather than her strengths. Initially stubborn and overly reliant on analysis, she gradually learns to balance intuition and teamwork. Adjusting to Earth's customs proves challenging, requiring Fuwa's power for communication at first. Her growth involves becoming more confident and open to new experiences, ultimately influencing Saman's culture positively. Key traits include empathy, introspection, and a conflict-averse nature, aligning with INFJ and Enneagram Type 9w8 classifications. She struggles with feelings of inferiority toward her accomplished twin brother, Lolo, whom her parents favor. Despite this, she deeply cares for her family and defends them when necessary.

Her relationships drive her development. With Hikaru, she transitions from initial hesitance and arguments to a close bond, learning about Earth through her. She encourages her alien teammate Yuni to embrace Earth's experiences. Prunce shares a trusting friendship forged during their mission. Family dynamics involve tension with her parents, Toto and Kaka, who compare her unfavorably to Lolo, though they later acknowledge her role as a Pretty Cure. Her boss, Kuku, initially dismisses her competence but is surprised by her heroic identity. Character-defining moments include her first transformation to protect Fuwa, using the Milky Shock attack, and overcoming self-doubt when saving Lolo from a hacked AI system on Saman.

Her story unfolds across the series and film. Early episodes depict her meeting Hikaru, gaining language abilities via Fuwa, and transforming into Cure Milky after vowing to protect Fuwa. The film shows her in a white turtleneck and hat during space adventures. She participates in group attacks like the Southern Cross Shot and Star Twinkle Imagination. Her Twinkle Style form elongates her hair and adds a tiara, while the movie introduces zodiac-based transformations. The epilogue reveals her returning to Saman as an inspector, aiding planetary improvements and reuniting with Hikaru during a space launch. Her name, "Hagoromo," combines "wing" and "robe," while "Milky" references the Milky Way galaxy.

Her transformation sequence reflects her alien heritage and personal growth. As Cure Milky, she surfs on a green, heart-shaped wave symbolizing the Milky Way's "silver river" concept, expressing visible joy. The sequence highlights her journey toward self-acceptance, with design elements like translucent bubble sleeves nodding to classic alien depictions.