Gunther Schultz is a second-year student at Attack Junior High School and part of the unauthorized Scout Regiment club. He possesses a tan complexion, short black hair, and large, bright eyes, typically seen in the standard school uniform. Outwardly serious and quiet, Gunther reveals a flustered side around those he finds attractive, reacting with visible blushing and internal fluttering. He shares a close friendship with Eld Gin, often together during club activities where Gunther frequently reads manga.

When Oruo Bozado bit his tongue and collapsed during an incident involving first-years retrieving Armin Arlert's confiscated futon, Gunther rushed to his aid. Expressing concern over Oruo's habit of biting his tongue approximately three times daily, Gunther later exposed Oruo's secret study habits after Oruo boasted about high grades without effort, revealing Oruo's mother confirmed he studied all night before exams. Gunther himself scored 71 points.

He joined fellow second-years in criticizing first-year students' appearances and behavior, specifically targeting Armin's hairstyle, leading to cleaning duties for the first years. On Sports Day, Gunther participated in shoulder wars alongside Oruo and Eld, carrying Petra Ral, and later assisted first-years with court cleanup. For a courage test, he disguised himself as a Titan model with Eld in the science room to ambush the first-year group. During the student council president election, he reluctantly served as Oruo's substitute.

At the school festival, Gunther waited in line for cheeseburgers, expressing a desire to meet the rumored pretty salesperson. He blushed persistently upon discovering it was Armin in disguise. He also watched Ilse Langnar's broadcast of Eren Yeager's mission to retrieve a cheeseburger from the principal's office, showing relief at Eren's success.