Yū Nishinoya, a second-year student at Karasuno High School, serves as the libero for the boys' volleyball team. Initially standing at 159.3 cm and later growing to 160.5 cm, he remains the team's shortest member. His appearance features wild, upward-styled dark hair adding roughly 10 cm to his height, with a bleached tuft falling over his forehead. He frequently sports brightly colored shirts displaying four-character idioms such as "One-Man Army" and wears an elbow pad on his right arm during matches. He attended Chidoriyama Junior High, playing volleyball there and earning recognition for his exceptional libero skills, receiving an award despite his team's elimination. He recalls competing against Kitagawa Daiichi Junior High, encountering Oikawa's powerful serves. Nishinoya chose Karasuno High because he admired the black gakuran uniforms and the girls' uniforms, combined with the school's proximity to his home. As a child, Nishinoya feared many things, including insects, dogs, birds, vegetables, and riding bicycles. His grandfather trained him to confront these fears, instilling the belief that fear wastes valuable experiences. This upbringing shaped his tenacity, though he retains dislikes for moths and onions. During his first year at Karasuno, he clashed with ace spiker Asahi Azumane after a loss to Date Tech where Asahi's spikes were consistently blocked. In a subsequent argument urging Asahi not to quit, Nishinoya accidentally struck the vice-principal, resulting in a one-week school suspension and one-month club suspension. Off the court, Nishinoya exhibits a highly energetic and impulsive personality. His boisterous behavior often leads to trouble, such as overenthusiastically approaching team manager Kiyoko Shimizu, resulting in an off-screen slap. Alongside teammate Ryūnosuke Tanaka, he frequently attempts to interact with Kiyoko, causing disruptions that draw reprimands, typically from captain Daichi Sawamura. He enjoys being called "senpai" by underclassmen and invents creative names for his receive techniques. Despite his exuberance, he feels shy around unfamiliar girls. During matches, his demeanor shifts to intense focus and calmness. Revered as Karasuno's "Guardian Deity" for his defensive prowess and ability to inspire teammates, his declaration, "All right, there’s nothing to worry about. All of you, keep your eyes forward. Because you have me guarding your backs," exemplifies his role in bolstering morale, particularly reassuring Asahi during high-pressure games. Nishinoya's libero skills are considered elite, acknowledged by opponents like Nekoma's Yaku. His signature move, "Rolling Thunder," involves a dive-and-roll receive to handle powerful spikes. He possesses exceptional reflexes, speed, and flexibility, enabling him to return seemingly impossible balls. Notably, he once used his foot to save a ball against Date Tech, a move that garnered widespread acclaim. He developed the "libero toss," an offensive technique where he sets for attackers like Asahi during synchronized plays, though it leaves the team vulnerable if blocked. Initially weak at overhand receives and float serves, he improved through dedicated practice with teammate Hisashi Kinoshita. His physical metrics include a fingertip height of 208 cm and jumping reaches of 302 cm (spike) and 290 cm (block). Nishinoya openly shared his childhood fears during Nationals to motivate pressured teammates. His relationship with Asahi is particularly significant; their dynamic contrasts in personality, height, and birthdays (Asahi: January 1; Nishinoya: October 10), yet they mutually support each other's growth. After high school, he retired from volleyball to travel the world.