Raki Kiseki, a second-year middle school student, transfers to Star Harmony Academy to pursue idol activities. Her fair skin complements rosewood eyes flecked with pastel yellow and baby blue, while pale khaki hair spills into thick pigtails secured by wrapped hair at the base, accented by a crimson headband. Standing at 154 cm, she celebrates her Sagittarius birthday on December 7 and holds blood type O. She savors bacon waffles with syrup, delights in shooting stars and daruma dolls, and dedicates herself to dress design, sewing, and watching idol performances. Sketching and experiencing good fortune rank among her specialties, though she grapples with computers and electronics.

Radiating bright energy and optimism, she peppers conversations with enthusiastic catchphrases like "Ciao!" and "I'm so lucky!" Natural luck grants her frequent lottery wins and serendipitous advantages, yet overreliance on fortune sometimes sparks complications. A fierce passion for fashion design fuels her ambition to launch the brand Maple Ribbon. Early attempts involved rushed, derivative creations—like a dress heavily inspired by Ichigo Hoshimiya’s Constellation Dress. Through experience, she learns that infusing designs with genuine emotion delivers joy, driving her toward originality and deeper appreciation for craftsmanship. Quick to admit faults and improve, she rarely shows anger except toward her sister.

Her journey ignites when her older sister, Aikatsu engineer Sāya Kiseki, gifts her a special Aikatsu Pass. While Sāya supports her dreams, she also uses Raki as a test subject for experiments. The pass triggers interdimensional travel, summoning doors that whisk her across idol realms. These adventures connect her with idols from academies like Four Star and Starlight, including Yume Nijino, Ichigo Hoshimiya, and Aine Yūki, catalyzing collaborations and growth.

Key relationships anchor her path. She deeply admires Aine Yūki and Mio Minato, who become interdimensional travel companions. Wakaba Harukaze partners with her in the unit Cheer Star☆ after a successful audition. Seeking design refinement, she apprentices under Asuka Amahane, who regards her as a pupil. She inspires Kokoro Kojima to embrace idol work and bonds with peers like Yume Nijino during events. Her dynamic with sister Sāya remains complex due to experimental tendencies.

Growth unfolds through layered challenges. She evolves from imitation to originality, exemplified by crafting costumes for Hibiki Tenshō’s theater troupe. Her dream crystallizes: using the Aikatsu Pass to bridge idols across dimensions, fostering mutual growth and "new Aikatsu" experiences. Participation in units like Cheer Star☆, seasonal groups (e.g., "Angel Sisters"), and collaborative Friends units such as "Lucky Strawberry" with Ichigo amplifies her impact. These endeavors cement her mission to unite idols through shared passion and effort.