Sayo Hikawa navigates life with disciplined precision and a serious demeanor, her uncompromising approach shaped by a lingering sense of inferiority toward her younger twin sister, Hina, whose natural talents once fostered emotional distance between them. Through shared experiences and growing mutual understanding, Sayo steadily mends their bond, confronting past tensions while striving to redefine their connection. A first-year law student at Keiho Women’s University, her history on the disciplinary committee underscores a steadfast commitment to order and self-imposed rigor. This ethos permeates her role as Roselia’s guitarist, where she relentlessly hones her craft to carve a unique musical identity, driven by the desire to stand alongside Hina as an equal. Her journey intertwines artistic ambition with a deeper quest to forge individuality beyond her sister’s shadow. Archery, gaming, and baking occupy her leisure time, each pursued with meticulous attention to detail. Despite her austere exterior, she harbors an affinity for fluffy animals and indulges in junk food, gum, and candy—though carrots remain firmly off her plate. Interactions with others often spotlight her preference for structure, yet her evolving relationships with bandmates and gradual reconciliation with Hina unveil a guarded willingness to embrace vulnerability and change. Her narrative traces a path from self-reliant isolation to tentative connection, balancing personal aspirations with the pull of familial ties. Collaborative musical projects with Hina and acknowledgments of shared purpose mark her incremental progress, yet her core—a resolute, earnest nature—remains unshaken, anchoring her growth without erasing the determination that defines her.