Rei Ryuugazaki begins his academic journey as a first-year student at Iwatobi High School, advancing to third-year before matriculating at Shimogami University. Born December 14 under Sagittarius, his physique evolves from 177 cm to 179 cm during high school, marked by a muscular build emphasizing triceps and abs. His distinct appearance combines short dark blue hair, purple eyes, and crimson hexagonal glasses, often accompanied by a crisply tucked uniform and a waist-strapped backpack. Initially a pole vaulter on the track team, Rei joins the swim club after relentless persuasion from Nagisa Hazuki. Though initially critical of swimming’s "lack of beauty," Haruka Nanase’s graceful technique inspires him to pursue the sport. His early reliance on theoretical calculations for angles and distances stifles progress until he adopts instinctive methods. As swim club captain following Haruka and Makoto Tachibana’s graduation, he leads the team to national competitions. Rei’s breakthrough comes when Gou Matsuoka challenges him to master swimming in a week. After struggling with initial strokes, he excels in butterfly, becoming the team’s specialist. Mentorship from Rin Matsuoka later expands his proficiency to all strokes, aided by training tools like kickboards. His rigorous practice yields personal records at nationals. Analytical and aesthetically driven, Rei prioritizes elegance in conduct and appearance. Though prone to theatrical self-doubt, he counters with tenacity. His polite speech occasionally fractures under emotional strain. Health-conscious habits include sushi, barley tea, and family-tradition melon bread, while avoiding supernatural themes. Nagisa’s playful persistence repeatedly pushes Rei beyond his comfort zone, fostering reciprocal growth. Evolving from critic to mentor, Rin guides Rei’s technical growth, culminating in Rei relinquishing his relay spot to mend team bonds. Respectful camaraderie replaces his initial awe of Haruka, while shared leadership deepens his bond with Makoto. A childhood library interaction with Asahi Shiina resurfaces at nationals, underscoring Rei’s subtle influence on others. Post-graduation, Rei continues swimming at Shimogami University while sustaining ties with former teammates. His arc traces a shift from rigid theorizing to embracing intuition, epitomized by tearfully acknowledging Haruka and Makoto’s departure. This growth cements his role as a unifying force and catalyst for peers’ achievements.