Arisu Hanazono is a human middle school student with short hair featuring a yellow-to-pink gradient, white skin, and dark pink eyes. She typically wears a sailor-style white top with a blue collar featuring a white stripe and a pink ribbon, paired with a long blue skirt trimmed in pink and blue shoes. In her transformed Fairilu state, her hair grows waist-length, and she gains a blue hairband with a bow featuring a pink heart, retaining her human-form clothing while sprouting heart-shaped wings with a pink, light blue, and yellow gradient.

She originates from Earth, living with her family: her mother, Ema Hanazono, and her older sister, Marie Hanazono, noted for skill in sports and academics. The surname "Hanazono" translates to "flower garden," derived from the Japanese words for "flower" (花) and "garden" (園). While walking home preoccupied by persistent worries about forming friendships, Arisu encounters a mysterious shop containing a Magical Pendulum and book. A hooded figure, Fairilu Guga, reveals the book's magic, prompting Arisu to purchase it. Reciting "Rilu Rilu Fairilu!" with the pendulum opens the book, releasing Fairilus Lip and Spica, who transport her to the magical world of Little Fairilu.

Within Little Fairilu, Arisu transforms into a Fairilu. Greeted by numerous Fairilus at a gathering place, she attends a tea party and confides her difficulty making friends. Encouraged to practice social skills, she successfully invites Fairilus Akoya and Hopper to join the event. To return home, she recites the magic words again, discovering a Fairilu Card upon her return. This pattern repeats: facing worries prompts her to use the Magical Pendulum, summon Fairilus, journey to Little Fairilu to resolve her concerns, and gain a new Fairilu Card upon each return. Through these experiences, she undergoes gradual personal growth, developing courage and problem-solving abilities.

Her story concludes with maturation into adulthood. As an adult, she loses the ability to visit Little Fairilu or interact with the Fairilus directly. The Fairilu Cards and her memories remain as mementos, symbolizing her developmental journey from a fretful adolescent to a resilient individual.