Hotaru Hiraiwa, a first-year student in Class 1-3 at Roubai Girls' Academy (seat 14), stands out as the shortest in her class, her petite frame and delicate, doll-like features frequently earning comparisons to an elementary school student. Whitish-blond hair cascades in voluminous waves around her face, complementing light blue eyes that mirror an air of quiet intrigue.

Beneath her gentle, kind demeanor lies an enigmatic unpredictability. She materializes in unexpected corners of campus, her conversations meandering through tangents that leave peers both charmed and perplexed. Though soft-spoken, she reveals flashes of athletic brilliance—darting across sports festivals with agile precision during badminton or basketball matches, or evading capture in tag games with such speed that even skilled classmates struggle to match her.

She shares a spacious residence near the train station with her older sister, though family details remain sparse. Her passions include practicing trumpet melodies, savoring pizza buns, and wandering Mount Hiraiwa, a namesake peak where she catalogues flora and fauna with encyclopedic knowledge of their ecosystems.

While interactions with classmates are seldom documented, her sweetness lingers in contrast to her mystique. No sweeping arcs redefine her character, yet her consistent presence—a blend of ethereal eccentricity and quiet warmth—cements her as an indelible, if understated, figure within the academy’s halls.