Madoka Kaguya, also known as Cure Selene, is a third-year student at Mihoshi Middle School and serves as the student council president. She comes from a distinguished family: her father holds a high-ranking government position, while her mother is an internationally acclaimed pianist. Madoka herself is a national champion in both piano and archery, and she also practices flower arrangement and tea ceremony while maintaining top grades. Her elegant demeanor and refined speech, including her signature greeting "Gokigenyou," have earned her the nickname "The Moon of Mihoshi Town" among her peers.

Despite her outward perfection, Madoka is a diligent and private person who works hard behind the scenes to meet the high expectations placed on her. She feels the weight of her family's legacy and strives to live up to her father's ideals, even though the constant pressure leaves her little room for ordinary teenage experiences. This inner conflict becomes central to her character: she is torn between her desire to be a perfect daughter and her own growing sense of self. When she first encounters the alien fairy Fuwa and the threat of the Notraiders, she hesitates to become a Pretty Cure because her father has taught her that the Kaguya family keeps no secrets, and she fears the deception. However, her determination to protect Fuwa and her friends ultimately leads her to transform into Cure Selene, the Pretty Cure of the Moon.

As a member of the Star Twinkle Precure team, Madoka brings a grounded, strategic presence. Her combat style is precise and calm, reflecting her archery training. She wields a crescent moon bow and arrow, and her signature attack is Precure Selene Arrow, which channels lunar energy. She also demonstrates quick thinking and negotiation skills, learned from observing her father in high-pressure situations.

Throughout the series, Madoka's relationships with her teammates help her grow emotionally. She shares a close bond with Elena Amamiya, who is in the same class and serves as a supportive friend. Her interactions with the more carefree Hikaru Hoshina and the alien Lala Hagoromo encourage her to embrace her own feelings and loosen the strict rules she has imposed on herself. A significant turning point in her development comes when she confronts her father's rigid expectations, learning that true strength lies not in meeting others' standards but in being honest about her own dreams and limitations. By the end of the story, she gains the confidence to balance her responsibilities with her personal happiness, embodying the moon's gentle but steady light.