Aika Hayase shines as a member of the Japanese idol group Sweet Diva, performing alongside Sakura Hagiwara, Elena Miyazawa, Yuuho Mochizuki, and Nanami Kanno. She sports long blue hair styled in high twin pigtails that cascade to her mid-back, typically tied with cheerful yellow ribbons. Her wardrobe alternates between Sweet Diva’s signature group attire and a vibrant yellow bikini edged with white linings for beach appearances.

Her personality radiates bright, cheerful energy akin to Sakura's, yet reveals a softer, more timid dimension. Aika shares particularly close bonds with her bandmates, most notably Yuuho Mochizuki as part of the subgroup "Puff Sleeves." Within Sweet Diva, she, Yuuho, and Nanami rank among the most popular members after Sakura and Elena. This warmth extends to comforting Sakura after wrestling losses and earnestly pleading for her return following conflicts with Elena.

Group dynamics showcase her concerns during workload discussions with manager Makoto Kirishima, where she voices reluctance about wrestling-themed appearances—contrasting Sakura and Elena’s enthusiasm. During Sakura’s debut match against Rio Kazama, Aika watches anxiously from the audience but turns away from Sakura’s defeat, deeming the spectacle unnecessary and longing for Sakura’s swift idol return.

After Sakura temporarily departs Sweet Diva for professional wrestling, Aika witnesses the resulting strain: missteps in rehearsals and Elena’s mounting stress. She later attends Sakura’s comeback match against Rio alongside fellow members. Though stunned by Sakura’s choice to wrestle with Berserk Wrestlers long-term, Aika respects the decision and preserves their friendship. She offers support, even as a guest commentator for future matches, while quietly hoping for Sakura’s eventual full-time return to Sweet Diva.