Madoka Kaguya, a third-year student and president of Mihoshi Middle School's student council, carries the epithet "The Moon of Mihoshi Town." Born into a prominent family—her father holds a government position, her mother is a celebrated pianist—she excels academically and claims national championships in piano, archery, flower arranging, and tea ceremonies. Her father's demanding expectations instilled intense stress and perfectionism, fueling indecisiveness and internal pressure while straining their relationship. This tension intensifies as she conceals her dual life: protecting the alien entity Fuwa and fighting as a Pretty Cure. Through experiences and friendships, she gradually learns to manage pressures, lower self-imposed standards, and assert her own choices.

Initially distant from classmates like Amamiya Elena, Madoka develops mutual respect with her after joining forces as Pretty Cure teammates, admiring Elena's dedication to her siblings. She views the alien Hagoromo Lala with early suspicion but later bonds with her over shared struggles with parental expectations, deepening their friendship.

Madoka’s journey as Cure Selene begins when she encounters Fuwa alongside the Star Twinkle team. Despite her duty to report aliens to her father, she chooses to protect Fuwa after witnessing its kindness. This resolve triggers her transformation into Cure Selene, Pretty Cure of the Moon, granting heightened senses, precision, and agility. Her signature attack, the Selene Arrow, channels her archery expertise into long-range strikes. Transforming requires the Star Color Pendant and Star Color Pen, activated by her catchphrase: "Good day" (ごきげんよう, "Gokigen'yō").

In civilian life, Madoka sports long layered purple hair with dark magenta ribbons and gentle blue eyes. She favors elegant indigo attire featuring crescent moon motifs on details like belt buckles or brooches. As Cure Selene, her hair thickens into lilac, secured by gold bands and a frilly crescent-adorned headband. Her costume includes a deep purple southern-cross bodice, layered skirt, crescent earrings, and snowflake-patterned boots. Alternate forms comprise Twinkle Style (longer star-decorated hair with a tiara), Capricorn Cure Selene (magenta-ombre hair, goat horns, heart accessories), and Sagittarius Cure Selene (ponytail, archery-themed gear with bow and arrow).

Within *Precure Miracle Universe*, Cure Selene and the Star Twinkle team are transported to space during stargazing. They ally with Hug! Pretty Cure and Kirakira Pretty Cure a la Mode against universe-threatening darkness, protecting Miracle Light creator Piton and battling antagonist Yango, who manipulates citizens via Dark Lights. Madoka emphasizes teamwork and precision, particularly in unified attacks requiring collective resolve. This experience reinforces her growth in leadership and pressured decision-making.

Her arc culminates in heightened self-assurance and independence, balancing family duties with her Cure Selene identity. She confronts her father about her choices, cementing her emotional maturity.