Arisa Ichigaya is a third-year student and student council vice president at Hanasakigawa Girls' High School, serving as the keyboardist for the band Poppin'Party. Her family runs the pawnshop Ryuuseidou, housed in a traditional-style building with a basement where the band often practices. This shop holds significance as the place where Kasumi Toyama discovered the "Random Star" guitar, a catalyst for the band's formation. Arisa's grandmother manages the shop, and Christmas celebrations are rare for them. Her deceased father left behind both the Random Star guitar and a notebook titled "BanG_Dream!" containing plans that influenced her path into band life, mirroring his own history as a band leader.

As a child, Arisa learned piano, attending the same music school as Tae Hanazono and Rei Wakana in the Pianist Course. She quit lessons due to waning motivation and the demands of studying for middle school entrance exams. Before joining Poppin'Party after Kasumi inspired her to restart keyboard playing, Arisa was a shut-in, spending most of her time at home helping in the pawnshop. Her frequent absences led to school rumors she was a ghost. This reclusiveness stemmed from a preference for solitude and self-professed laziness, despite her excellent grades.

Arisa possesses long, slightly curled blonde hair, usually styled in two pigtails secured with ribbons or bands. Her bangs spread across her forehead, with a few curled strands sticking upward; her forelocks are pinned back with cross-shaped clips. She has gentle light brown eyes. Her fashion favors mature, feminine styles with lace or floral details and long skirts. Her initial outfit is a black blouse with sheer off-the-shoulder sleeves and a white skirt featuring lilac floral patterns. In colder weather, she wears a black sweater with a white lace overlay, a light-brown high-waisted skirt, black tights, and white pom-pom hair ties, accessorized with a four-flower necklace. Her summer attire includes a sleeveless white-and-black striped shirt, a yellow high-waisted skirt with a belt, and black ballerina shoes with white ankle socks, plus a small necklace with a red ribbon.

Personality-wise, Arisa is introverted, moody, and sharp-tongued, frequently arguing, especially with Kasumi. This often masks her difficulty expressing genuine feelings. Beneath a cynical exterior, she is deeply caring and easily flustered by compliments, blushing and stammering when praised by bandmates. She forms strong attachments, experiencing visible jealousy or loneliness when separated from close friends, though she denies these emotions. Her hobbies include tending to bonsai plants—each named and spoken to daily, like Tamagawa, Tonegawa, and Popipa—and browsing the internet. She dislikes leeks but enjoys anmitsu, brown rice, and hard-boiled eggs. She habitually overpacks for trips, always carrying a favorite fluffy towel.

Her character development traces an evolution from a loner who rejected help to someone valuing companionship. Early interactions involved exaggerated politeness to maintain a refined image, as seen with Eve Wakamiya and Misaki Okusawa. Friendship with Kasumi gradually opened her up, fostering kindness and social engagement. Key growth moments include organizing a surprise party with Tae for Poppin'Party's anniversary, reconciling after conflicts like the "Double Rainbow" band story, and supporting Kasumi during emotional challenges. Her bonds with bandmates deepen, shown through flustered reactions to physical affection from Eve or Lisa Imai. Unspoken care for Kasumi manifests in tsundere behaviors: acting cold to hide a desire for closeness, jealousy over Kasumi spending time with others, and panic when hugged by Kasumi after their first live performance. The lyrics of her solo song, "Su-Suki Nanka Janai!", heavily imply unresolved feelings toward Kasumi. Her pragmatic nature often contrasts with other characters' idealism, creating a dynamic where she grounds the band's whimsical ideas while reluctantly participating.