Yū Setoguchi, a third-year Sakuragaoka High School student and Movie Research Club member, stands 178 centimeters tall with a lean build, short wavy brown hair, and striking purple eyes. His wardrobe adapts to the seasons: crisp school uniforms with open blazers and tucked-in shirts in colder months, replaced by untucked shirts with loose buttons and no tie when temperatures rise. Calm and collected, Yū exudes a mature, approachable aura, though he guards his emotions closely. This reservedness extends to his longtime affection for childhood friend Natsuki Enomoto, whose feelings he reciprocates but conceals behind platonic camaraderie. Privately, he monitors rivals like Koyuki Ayase, balancing possessiveness rooted in their shared history with respect for Natsuki’s independence. Protective instincts define his relationships. He acts as a responsible yet indulgent older brother to sister Hina, discouraging her romantic ventures due to her perceived naivety. Childhood friends Sota Mochizuki and Haruki Serizawa see him as a steady confidant—Sota envies his popularity, while Haruki’s flirtatious habits create occasional friction. Classmates like Akari Hayasaka and Miou Aida interact with him politely but only during group tasks. Tensions escalate when Natsuki initiates repeated "practice" confessions to mask her true feelings. Yū’s avoidance of his emotions sparks conflict, such as criticizing her concert-date outfit. After interrupting Koyuki’s confession to Natsuki, a heated argument forces both to confront their mutual longing, culminating in Yū accepting Natsuki’s genuine confession. Their romance preserves its playful foundation, though Yū grows more openly affectionate over time, leading to marriage and two sons. Beyond relationships, Yū engages moderately in the Movie Research Club, aspiring to produce films. He enjoys video games, casual outings, and frequent ramen excursions. Minor inconsistencies include occasional height discrepancies and a fleeting comment about viewing Natsuki’s gender identity as uniquely compelling rather than traditionally romantic—a nuance that ultimately harmonizes with their enduring bond.