Uzuki Toreishi, the fourth Toreishi sister, is 15 during the main events and 16 in the later '95 Song of the Wind timeline. Her blood type is O. Physically more developed than her older sister Satsuki, a contrast fueling Satsuki's insecurities, Uzuki sometimes plays on this awareness. She aspires to become a "Fever Girl" and anticipates further physical maturity. Despite often projecting a relaxed or seemingly slow demeanor, she reveals surprising insight, offering incisive—sometimes unintentionally sharp—critiques of her sisters.

Her personality includes distinctive quirks, like her dedicated hobby involving marimo balls. She dotes on these algae balls, singing to them and occasionally carrying them in a baggie. Within the family, she frequently interacts with her sisters, serving as a contrast to Satsuki's anxieties and becoming a common target for Mina's mischief due to their closeness in age.

Professionally, Uzuki balances dual roles as an idol singer and a combat pilot. She operates the large HB-04 multirole bomber, carrier, and supply aircraft, which requires JATO modules for takeoff due to its size and weight. This specialization in heavy aircraft reflects her preference, with the F-4 Phantom noted as her favorite. During missions, she typically pilots the HB-04 with her youngest sister Mina acting as co-pilot, radar intercept officer, or systems operator; Mina's attack helicopter often deploys mid-air from Uzuki's craft. In the group's musical performances, Uzuki uniquely performs solo songs.