He was a man of average height and light hair, which was shown to be light grayish in anime. Which was covering his forehead in the form of bangs, ending right above eyes. His eyes were dark blue. He looked somewhat older and wiser than Eren. He was shown to be wearing the standard trainee uniform.
Mylius Zeramuski was a graduate of the 104th Trainees Squad. After the second attack of the Colossal Titan, he was assigned to the middle guard along with Eren Yeager and Armin Arlert. Shortly after the squad's deployment, the group was attacked by an abberant Titan, which resulted in the death of Thomas Wagner. This caused Eren to attack the abberant in a rage. He warned Eren not to go alone, which in turn caused his squad to pursue and try to help him. Mylius was then eaten by a Titan when the squad engaged the Titans in the Trost District.