Rintarō Suna attends Inarizaki High School as a second-year student and serves as a middle blocker on the school's volleyball team. He stands 185.7 cm tall, weighs 73.2 kg, and possesses dark brown hair typically styled with a middle part and stray strands sticking up. His features include narrow grayish-yellow eyes and thin eyebrows, often paired with a blank or deadpan expression. Following a timeskip, his hair shortens slightly and his physique becomes more muscular. Hailing originally from Aichi Prefecture, Suna transferred to Inarizaki in Hyōgo after being scouted. His personality blends a quiet, outwardly indifferent demeanor with analytical sharpness and dry humor. Internally, he frequently makes sarcastic remarks or snide comments about teammates like Kita or opponents such as Tsukishima and Tanaka, though his facial expression remains neutral. Suna tends to slack off during matches when his team has a substantial lead but refocuses instantly if he senses Kita observing him. He habitually records or photographs the Miya twins' arguments for amusement. As a middle blocker, Suna exhibits exceptional athletic abilities, including high-level jumping, speed, and stamina. His signature skill is the "wide-range spike," which exploits torso rotation to generate sharp angles and manipulate blockers. This technique allows him to deceive opponents by altering his body direction mid-approach, creating spikes that penetrate defenses effectively; he was never successfully stuffed during the Spring National Tournament against Karasuno. Defensively, he demonstrates rapid blocking reflexes and sharp game sense, enabling him to adapt to opponents' tactics—such as anticipating Kageyama's sets to shut down Tanaka. Tsukishima acknowledges him as one of the best middle blockers at Nationals, particularly noting his speed and analytical blocking approach. Suna's relationships within Inarizaki reflect his pragmatic nature. He maintains cautious respect for captain Shinsuke Kita, acknowledging Kita's observational skills and striving not to disappoint him. While finding the Miya twins' antics bothersome, he interacts with them regularly, responding to Atsumu's taunts and occasionally mediating their quarrels. He also provides insights to first-years about Kita's limited playtime before his third year. Post-graduation, Suna joins the professional team EJP Raijin in Japan's V.League Division 1 as a middle blocker, playing alongside Washio and Komori. In 2022, he participates in an All-Star match on Team A, observing the instant rivalry between Atsumu and Oikawa with detached amusement. Beyond volleyball, Suna favors jelly fruit sticks (Chūpet) as his preferred food. His pre-timeskip concern about avoiding entanglement in the twins' antics evolves into post-timeskip regret over his responses.