Hikawa Sayo is a first-year student at Keiho Women's University, as well as the guitarist of Roselia. She was a member of both the student council and disciplinary committee at Hanasakigawa before her graduation. She is the older and more serious twin of Hina. Sayo has slanted green eyes and long, navel-length light teal hair with her forelocks worn behind the ear with a curl on the end. Her bangs are neatly parted with the exception of a single loose lock falling down her face. Her casual attire is simple with a tomboyish, yet cute tone, mixing pale and dark shades. A serious and fussy girl, Sayo can be somewhat cold in nature, even towards those she is close to. She never cuts corners or accepts shoddy workmanship, and is diligent in practice of any kind. She tends to stubbornly deny liking or being fond of certain things, such as fluffy animals or french fries. In comparison to her sister Hina, Sayo is fairly stiff and sharp, and is highly stubborn when trying to do what she believes is best for others. She speaks formally and addresses most people by their last names, except for her sister and Tomoe, whom she refers to as "Tomoe-san". Like Yukina, she can be prone to make snide or frank remarks, though often these remarks do not reflect how she actually feels. Despite this she is also shown to be prone to falling for weird explanations, especially shown in Beatin' in the Rain. As the story goes on, especially after she and Hina resolve their issues, Sayo starts becoming softer and showing her kind nature more, as well indulging herself in side activities more often, whereas in the past she would scold Ako and Lisa for wanting to spend their free time on anything but practicing. She is also more willing to extend a helping hand to others, such as shown in the Melody of the Dignified Wind event, where she began giving Touko guitar lessons.