Along with a blue neck tie, Erwin is portrayed with masculinity and the defined thickness of his eyebrows. He has blue eyes and blond hair styled in an undercut that he keeps parted on the left side. Erwin is seen wearing a pair of brown slacks, dress shoes, and a white long-sleeved shirt underneath a light brown suit.
He has concerns regarding how the school deals with the Titans, however, his true feelings towards the school's priorities are not easily understood by most.
Erwin welcomes the first-years on the first day of school.
Erwin appears behind Eren in the school at night and asks him what he sees, scaring him in the process. He apologizes and introduces himself as the advisor for the Attack Junior High Scout Regiment. When the first years head to the designated classrooms after being assigned to groups, Erwin announces the start of the 57th Test of Courage, the Scouts club's customary event for new club members.
At the end of the test, after a girl with white clothes is mentioned, Erwin questions Eren about what he saw, stating the school's Seven Wonders No. 7 is a girl who went missing during a test of courage, and unaware she had become a ghost, is said to still roam around looking for someone to scare.
Following the election for a new student council president, Erwin is present for the candidates' final speeches.
During the school's 104 festival, after hearing trembles on the ground, Erwin asks another teacher, Nile, to deploy all staff, in preparation for a Titan invasion, before a horde of Titans appears and steals all of the food stands.
Erwin later attends a meeting with other teachers to discuss the situation subsequent to Eren's successful attempt at retrieving his cheeseburger from the principal. When an enraged Nile states that Eren and the others have disregarded the school rules by going against the principal, Erwin believes they may now have a big chance for the human students to have a fun school life, as they have never imagined humans going against Titans, adding the fact that human students were able to take that chee-burg back from the Titans serves as a big step forward, calling for them to start reconsidering the school rules, and that this time, it is their turn to attack.