Kōshi Sugawara, commonly called Suga, holds the vice-captain position for Karasuno High's volleyball team in his third year. He stands approximately 174.6 cm (5'8.7") with a slender build, light grey hair, hazel-brown eyes, and a distinctive birthmark mole beneath his left eye. A gentle smile typically characterizes his appearance, though it transforms during moments of high emotion. Sugawara started playing volleyball at Nagamushi Junior High alongside Daichi Sawamura and Asahi Azumane. The trio entered Karasuno High aspiring for national tournaments, only to face early setbacks from the team's decline—early tournament eliminations and lack of coaching. These challenges solidified their determination to rebuild. Initially Karasuno's starting setter, Sugawara was later supplanted by first-year prodigy Tobio Kageyama. Unlike many third-years who retired, he persisted with club activities, telling a teacher he sought no future regrets. His dedication focused entirely on contributing to the team's success, irrespective of his role. His personality blends perceptiveness, strategic intelligence, and a calming influence. He frequently devises tactical innovations, including hand signals for synchronized attacks and coded phrases like "bring it" to trigger Kageyama and Hinata's quick attack. He also created the "Calculated One-Point Two-Setter" tactic enabling five spikers during plays. Off-court, he tutors teammates and uplifts team spirit. Yet, he displays mischievous tendencies—like encouraging Hinata to crash a training camp—and occasional aggression, smacking teammates to motivate them. During frustration, such as after losses, he exhibits uncharacteristic pouting or rambling. Sugawara's gameplay emphasizes reliability and unpredictability. Functioning as a pinch server, he targets difficult reception zones to disrupt opponents' spikers, notably used against Shiratorizawa's Kyōtani. Though physically average (rated 2/5 in power, jumping, stamina, and speed), his game sense (4/5) and technique (4/5) compensate. Limited official match experience made him an unknown element opponents struggled to analyze. Post-graduation, Sugawara becomes an elementary school teacher in Miyagi. By 2018, he remains connected to volleyball, attending an Argentina vs. Japan Olympic match with former teammates. As of July 2025, he is 31 years old. Notable trivia includes his preference for extremely spicy mapo tofu and enrollment in college-prep classes with Daichi. His zodiac sign is Gemini. Additionally, he won a 2015 "Best Dresser" award at a Haikyuu!! event. His surname was inspired by creator Haruichi Furudate's former colleague "Suga-san".