Along with her ginger-colored hair and golden eyes, Petra wears a yellow vest and a green bow on top of her white long-sleeved shirt and blue uniform skirt.
She is a member of the Attack Junior High Scout Regiment. Petra acts as an older sister figure to all the students. However, when Oruo is around, she becomes sharp, merciless, and no-nonsense. She also gets irritated when Oruo imitates Levi.
The day of the test results, Petra greets Eren, Mikasa, and Jean at the club room. When Eren asks about Oruo's problem, Petra warns him not to continue for Oruo is becoming annoying when he brags about his test results. Petra scores 82 and hits Oruo for his boastful complaints.
Along with the Scout Regiment club members, she scolds the first years for their behavior and looks, claiming that Sasha is an example of breaking the rules of appearance with an improper skirt length and an embroidery on her socks. She also nags Armin about the different accessories he uses to decorate his bag. As Eren yells at the same time of the arrival of a bunch of disheveled members, Petra snaps and orders the first years to do some cleaning chores.
After Levi challenges the first-years on Sports Day, Petra along with her classmates participate in the games. The shoulder race has come, and Petra and her team compete against all years, including the first years. Her troop makes their way through the race, as Mikasa violates all sorts of rules in order to distract Petra. Angered and in a state of distraction, Eren grabs her bandana and her team. With their defeat, Petra and the other second years offer a hand to help Eren and the gang, explaining that the upperclassmen the previous year had done the same and they are just returning the favor.
For the night of courage test, Petra is present when Hange explains the rules. She disguises herself as Mona Lisa, goes to the art room and waits for Eren's group to scare them. After a chase at the gym, Petra and her classmates reveal themselves.
During the school festival, she waits in line with Oruo, Eld, and Gunther to taste the cheeseburgers made by Eren's class. They are greeted by Armin, dressed like a woman, which surprises them. She forcefully puts a cheeseburger in Oruo's mouth to make him stop talking.
After the sudden arrival of the Titans, which results in the stealing of food stands, she attends an emergency meeting in the Scout Regiment club room with the other members. She tells Eren to follow Levi's decision and to not intervene. Along with the other Attack Junior High Scout Regiment members, Petra follows the Wall Cleanup Club progression in the small city before the principal's office. She is later seen shedding tears after Eren climbs out of the Colossal Titan's mouth.
- Oruo Bozad - She is often irked by Oruo's typical behavior, which involves big-talk and poor imitations of Levi. They usually do not get along due to their different personalities, however, they appear to be close friends nonetheless.
- Levi - Petra has a high level of respect for Levi, who is in the same club as her.