Arisa Ayase, also called Alisa Ayase, is Eli Ayase's younger sister. Her Russian heritage comes from her grandmother, and she grew up in Russia, leading to limited knowledge of Japanese daily customs—like once buying oden from a vending machine thinking it was a drink.

She has light blonde hair falling to her shoulders, blue eyes, and a slim build. A snowflake-shaped hairpin often adorns the right side of her hair, and she typically wears school uniforms with neckerchiefs.

Arisa intensely admires the school idol group μ's, particularly Eli and Umi Sonoda. She attends their performances multiple times, rewatches recordings constantly, and describes how their music sparks strong positive feelings. When Umi initially denies her μ's membership, Arisa shows clear sadness, later brightening when Umi acknowledges it.

Her personality blends cheerfulness with bluntness. She openly questions Eli's student council speech in Season 1, doubting it reflects Eli’s true wishes. At home, she discusses μ's shows with Eli, stressing how the group’s hard work and joy motivate her.

Arisa shares a close friendship with Yukiho Kosaka, Honoka Kosaka's younger sister. They watch μ's performances together, study jointly for entrance exams, and regularly hang out. After both pass exams for Otonokizaka Academy, Arisa initially plans to join μ's but later tells Honoka she and Yukiho will form a new idol unit instead. They decide this upon realizing the "μ's they love" is a distinct entity they respect, not something to join.

She remains an active audience member during key events like the Love Live! competition and graduation shows, supporting μ's while focusing on her own journey with Yukiho.