TV-Series
Description
Biwa Hayahide is a horse girl at Tracen Academy, distinguished by her remarkably thick, wavy silver hair whose substantial volume frequently attracts commentary, making her sensitive to perceived remarks about her head size. She wears signature red semi-rimless glasses, stands 171 cm tall, and possesses precise measurements of 93-61-88 (bust-waist-hips) with a 25.0 cm shoe size.

Her background revolves around being the older sister of prodigious racer Narita Brian, a relationship blending admiration with quiet envy as Biwa strives to establish her own identity separate from her sister's legacy. She shares a close family bond, recalling childhood matching hairstyles with her sister and their mother, and her family runs the "Heiwa Sake Shop" liquor store. At the academy, she forms the pivotal "BNW" trio friendship with Narita Taishin and Winning Ticket, sharing academic and racing endeavors. She rooms with T.M. Opera O, frequently discussing hair care challenges stemming from Biwa's difficult-to-manage hair.

Biwa's personality embodies logical precision and analytical rigor, epitomized by her pursuit of a "Formula of Victory" for racing. She tackles challenges methodically, prioritizing actionable results. Despite her calm exterior, she harbors insecurities about her hair volume and head size, often misinterpreting idioms like "standing head and shoulders above" as personal criticisms. She aspires to express herself more openly and takes pride in impeccable task completion. Academically, she excels across all subjects, particularly mathematics and sciences, and demonstrates strong organizational skills. Her weaknesses include rainy season difficulties when her tail easily snags on clothing.

As a racer, Biwa specializes in mid-to-long distances on grass tracks, favoring a front-runner (senko) strategy. Her attributes highlight exceptional intelligence (97) and stamina (93), with growth bonuses in grit and intelligence. She avoids dirt tracks where her proficiency is notably lower. Her racing outfit, "pf.Victory formula...", features a daringly slit skirt with cut-outs revealing skin beneath spats, knee-high socks, and garter belts, reflecting her calculated persona.

During Season 2, Biwa competes as a significant rival to Tokai Teio in the Arima Kinen race, showcasing strategic prowess but suffering a narrow defeat. Beyond the main series, she appears in spin-offs like relay races and food contests, often depicted rapidly eating bananas—her favorite food, consumable in under five seconds. In the 2024 game scenario "Run! Mecha Umamusume," she assists a scientist developing robotic horse girls, adopting a cyberpunk outfit and ponytail hairstyle.

Trivia notes her side role as a hairspray reviewer due to her hair struggles, her habit of sleeping with glasses placed precisely top-left, and her encyclopedic knowledge of rivals' preferences. Her real-life counterpart, a gray racehorse (1990–2020), inspired her banana affinity and head size jokes; the actual horse loved bananas and had a fluffy winter coat accentuating its head. Despite expectations for a sibling showdown with Narita Brian at the 1994 Arima Kinen, Biwa retired before the race occurred.