Asahi Shiina possesses messy red hair and distinctive rose-colored or aubergine eyes. His height increased dramatically from 155 cm in junior high to 179-183 cm by university. Born April 18th, his Aries nature brings determination, enthusiasm, and occasional impulsiveness. Frequent relocations marked his childhood, moving to Iwatobi before junior high and transferring away during his first year there. His family includes father Sohei Shiina, older sister Akane Kurimiya, brother-in-law Kon Kurimiya, and nephew Tsukushi Kurimiya. His father was a competitive swimmer who won trophies alongside Rin Matsuoka's late father; Asahi swam briefly with Rin as a preschooler, though the memory is hazy. Bright and energetic, Asahi acts as a "mood maker," expressing himself vibrantly and often comically pushing his luck. Competitive and driven, he motivates himself during athletic challenges by declaring "I am a genius," a habit persisting into university where friends like Ikuya Kirishima tease him. He avoids conflict but shows fierce loyalty, especially supporting teammates in difficulty. In junior high, he recruited Haruka Nanase, Makoto Tachibana, and Ikuya Kirishima into the swim club upon learning of their elementary swimming background. Initially a butterfly specialist, he developed a mental block against freestyle after being overwhelmed by Haruka's ability. Encouragement from Rei Ryugazaki and Nao Serizawa helped him overcome this and accept his limits. Aspiring to leadership, he became captain of Kazami High School's newly formed swim club, guiding the team to regional competitions. Reuniting with Haruka and Kisumi Shigino at Hidaka University, he joined the swim club, expanding his focus to include freestyle alongside butterfly. His journey continues through collegiate competitions and national meets, maintaining dedication to swimming and team bonds. He prefers meat dishes, especially ginger pork, and dislikes broccoli. His favored color is golden yellow, and he uses hair wax. He excels in science and physical education but struggles with mathematics. His symbolic animal is the ribbon seal, and his image number is 05.