Keishin Ukai, grandson of Karasuno High's legendary former volleyball coach Ikkei Ukai, initially presents a reluctant figure. He manages his family's store, Sakanoshita Market, often projecting a gruff, lazy demeanor—reading a newspaper with his legs on the counter or yelling at noisy customers. His appearance features dyed blond hair (reverting to natural dark post-timeskip), brown eyes, a headband, and two piercings on his left ear, removed during volleyball activities. Ukai attended Karasuno High eight years prior to the main events, playing as a setter for the volleyball team. He rarely played until the official setter's injury, an experience leaving lingering frustration about being overlooked for a younger player that later informs his coaching. He continued volleyball in college and joined a Neighborhood Association team post-graduation. Despite this deep connection to the sport, he initially resisted coaching Karasuno, citing nostalgia and a desire to preserve his high school memories. Persistent requests from faculty advisor Ittetsu Takeda, leveraging Karasuno's upcoming practice match against rival Nekoma High, secured his reluctant agreement to coach temporarily. Ukai's competitive nature and unresolved rivalry with Nekoma—particularly their coach, Nekomata—motivated his involvement. Initially viewing coaching as babysitting, he committed fully once engaged, rearranging his work schedule for practices. As coach, Ukai balances pragmatic analysis with mentorship. He organized a practice match against his Neighborhood Association team to assess players' strengths and weaknesses, identifying receives as Karasuno's critical flaw. His strategic acumen, honed mentoring underclassmen in high school and college, allows tailored training regimens, like adjusting Hinata and Kageyama's quick attack to counter blockers. He makes difficult choices, such as benching third-year setter Sugawara for Kageyama, respecting Sugawara's selflessness in prioritizing team advancement. Ukai's coaching evolves through interactions with his grandfather, Ikkei, whom he physically resembles and who occasionally advises him. Though initially estranged, Ikkei expresses pride in Ukai's natural mentoring abilities. Ukai's rivalry with Nekomata deepens after Karasuno's practice match loss, solidifying his long-term commitment to coaching. He guides the team through tournaments like the Interhigh, emphasizing preparedness without intimidation against powerhouses like Shiratorizawa. Post-timeskip, Ukai continues coaching Karasuno while managing Sakanoshita Market, demonstrating enduring dedication to both the team and his community. His development reflects a shift from reluctance to genuine investment in the players' growth, driven by competitive fire and underlying care for their success.