Keishin Ukai, grandson of Karasuno High's legendary former volleyball coach Ikkei Ukai, attended the same school and played setter for the team. He typically remained on the bench during official matches, wearing jersey number 2, until the primary setter's injury forced him into play. After graduation, he continued volleyball in college and later joined a Neighborhood Association team. He professionally manages the family-owned Sakanoshita Market, inherited through his mother. Initially resistant to coaching Karasuno's volleyball team, Ukai repeatedly declined faculty advisor Ittetsu Takeda's persistent requests. He cited a desire to protect his high school memories and doubts about matching his grandfather's legacy. Takeda pursued him based on the Ukai family name and Ukai's recognized strengths in mentoring younger players and analyzing opponents from his high school and college days. Ukai's competitive spirit ultimately swayed him; learning of a practice match against rival Nekoma and its coach, whom he had faced as a player, led him to accept the position temporarily. As coach, Ukai focused on strategic growth and addressing weaknesses. He arranged a practice match against his Neighborhood Association team to evaluate Karasuno, pinpointing receives as their major flaw. His tactical flexibility was evident in devising the synchronized attack to broaden offense and refining the freak quick attack to counter strong blockers. Ukai prioritized pragmatism, choosing first-year setter Tobio Kageyama over third-year Kōshi Sugawara for the starting lineup after Sugawara's selfless recommendation, influenced by Ukai's own past frustration as a benched upperclassman. Ukai's coaching blends gruffness with deep commitment. Despite complaining about the time, he adjusted his work schedule to early mornings to attend team practices. His competitiveness, especially against Nekoma, motivated him to continue coaching after their practice match loss, vowing to defeat them nationally. While often appearing lazy or irritable managing Sakanoshita Market – yelling at noisy students or skipping inventory – he occasionally showed kindness, like giving players free energy bars. Visually, Ukai has brown eyes. He initially sported dyed blond hair, a headband, and two ear piercings (removed during games and practices), with his resemblance to his grandfather noted. Post-timeskip, his hair returned to its natural dark color as he continued coaching and managing the store. Ukai's relatability to players stems from his recent high school experiences. At 26 during his initial coaching tenure, he empathized with challenges like bench warming or split-second in-game decisions. This perspective helped him mentor players through failures and opportunities, enabling reserves like Tadashi Yamaguchi to contribute in critical matches. His growth culminated in leading Karasuno to nationals, fulfilling a legacy intertwined with his grandfather's influence and the revived Nekoma rivalry.