|Knock it off! Are you on a picnic or something?! We're outside the Walls, you know!|
|— Gunther to his team mates|
Gunther was a man of average height with a slightly darker skin tone. He wore a short crop of brown hair that was kept to a point on the back of his head. As most of the soldiers, his attire consisted of a short light brown leather jacket with the badge of the Scout Regiment on both shoulders, on the front left pocket and on the center of the back, a light-colored shirt, a dark brown sash around the waist covering the hips, white pants and dark brown knee-high leather boots. Additionally, he was often seen wearing a green cape that the soldiers usually use for travelling with the symbol of the Scout Regiment on his back.
Being a soldier of the Scout Regiment who survived multiple encounters with Titans significantly affected Gunther's personality. According to Levi, Gunther was chosen to be the part of the Special Operations Squad not only for this strength, but also due to the fact that he did not completely trust Eren Jaeger. Even though Gunther and others were able to live through because of their ability to always expect the worst in any situation, they did not turn into heartless beasts as it was not easy for them to point their blades at Eren.
In the Special Operations Squad, Gunther seemed to be the most reasonable one. After Eren's unintentional transformation into a Titan, he was the only one to ask Eren for proof that he is not hostile. In contrast, Oruo threatened to kill him and Petra thought of Eren as dangerous while worrying about Levi's life. However, he was shown to be irritated when his comrades and Eren were jokingly mocking each other about having wet their pants, implying he also possessed a stern side and did not take kindly if a soldier did not focus on the task at hand.
Gunther participates in the 49th expedition beyond the Walls. When Hange Zoë breaks away from the regiment to pursue a Titan on her own, Erwin sends Levi's squad to keep her safe. They pursue the Titan to a clearing where it is killed, and subsequently discover the headless corpse of a soldier seemingly enshrined inside of a tree
After the post-Trost District battle trial to decide Eren's fate concludes with Eren joining the Scout Regiment, the Special Operations Squad is chosen to look after Eren. Gunther, along with the rest of the squad, then accompanies Eren to the former HQ of Scout Regiment, which will now serve as a hideout for Eren. After their arrival, Gunther and Eld notice that the HQ has not been properly maintained due to being unused. Due to that, Levi orders everyone to begin cleaning. Later that day, the squad discusses the upcoming expedition, with Gunther noting that it is happening too suddenly. When Hange arrives and Eren asks her to explain her experiments with Titans, Gunther and the rest quickly leave the room, already knowing a thing about Hange's speeches.
The next day, Gunther, along with the rest of the soldiers, arrives to the crime scene after being notified about the killings of Sawney and Beane. After hearing that the culprit disappeared using their omni-directional mobility gear, Gunther wonders if it was plan prepared by two or more people. After the investigation is done and the culprit is not found, Eld and Gunther discuss the upcoming induction ceremony, asking Eren whether any of his classmates will join, but Eren is unable to answer with certainty. Gunther is then present at the said ceremony, listening to Erwin's speech.
Levi finds a way to contain Eren in his Titan form without killing him, allowing Hange to run experiments on him, which Gunther and the rest of the squad monitor. Eren is unable to transform for some reason, but later triggers his transformation while attempting to pick up a teaspoon. Gunther and the rest of his squad mates immediately prepare to kill Eren, believing he has betrayed them, but Levi keeps them at bay. Later, Hange reveals to everyone the secret behind Eren's transformation. Realizing their mistake, Gunther and others bite their hands as a form of punishment, showing that they can trust each other.
One month later, Gunther is part of the expedition that heads into the Titan territory. Prior to the expedition, Gunther explains the plan of the expedition to Eren. When Eren questions the meaning of his power, Gunther asks him if Eren understood Erwin's question after the killings of Sawney and Bean, revealing that each of them was asked the same. Gunther concludes that there must be a hidden objective of this expedition.
As the time progresses, the news of a mysterious Titan killing the soldiers reaches the Levi Squad just as Gunther and others witness the black smoke signal, knowing that an abnormal Titan is near their position. Eventually, they enter the forest. Eren questions this, but then notices Gunther and others also do not know what is going on. At that moment, the mysterious Female Titan reaches their location. As they are being chased, in panic, Gunther yells out that they cannot escape inside the forest. He and the other squad soldiers beg Levi for orders, proposing to take the Titan down as it slaughters the reinforcements from behind. Levi, however, just shoots a sound grenade to calm them down, reminding them of their job. Eren finds himself to be unable to comply with the orders as he watches more soldiers to be killed. His intentions are made clear when he is about to bite his hand. Levi tells him to choose whether he believes in himself or the squad.
Eren decides to go with the squad. Gunther then notices that the Female Titan is accelerating and as it is about to catch up with them, they reach the location of Erwin and other soldiers who manage to trap the Female Titan, much to the surprise of Gunther and the squad. They then brag to Eren, claiming that it is thanks to the power of the Scout Regiment that they managed to capture their foe.
Seeing a flare that indicates the regiment is retreating, the squad begins making their way out of the forest. On their way to rejoin with Levi, Eld teases Petra and Oruo for peeing their pants on the first expedition, but Gunther scolds them for carelessly chatting in the middle of the Titan territory. They notice another signal flare and thinking it is shot by Levi, they fire their own one. However, Gunther realizes too late that it is not Levi to prevent the mysterious attacker from slicing his neck, killing him instantly.
Although never shown in direct combat, as an elite soldier chosen for the Special Operations Squad under the command of Levi, Gunther was presumed to be quite strong. He was a skilled warrior with a high Titan kill, having a record of 47, of which 40 were obtained in teams and 7 in solo. He was shown to be quite proficient in the usage of omni-directional mobility gear and displayed a certain degree of intelligence, being able to deduce that Erwin did not reveal the true objective of the expedition.
- Levi - Levi seemed to have at least professional respect for Gunther, as he hand-picked him to be part of the Special Operations Squad due to his high-level skill of killing Titans. Gunther was obedient and loyally executed the orders that Levi gave his team. Upon looking at Gunther's corpse, Levi was ultimately hurt at the loss of a comrade.
- Eld Gin - Alongside Eld, Gunther showed that he did not lack a humorous side as he would sometimes join in on banterous conversations that Eld would start. Nevertheless, Gunther blatantly put his trust in Eld, respecting his decisions and vice-versa. They seemed to have an easygoing, relaxing friendship and did not stop confiding in each other until the very end.
- Oruo Bozad and Petra Rall - Gunther shared a close friendship with the two having been working together for several years in the Scout Regiment. Although, Gunther did find the pair annoying when they were bickering, occasionally reprimanding them each time they did so.
- Eren Jaeger - Being the newest addition to the squad at the time, Gunther was a little bit wary of Eren after acknowledging that he could turn into a Titan. Eren looked up to the people of the Special Operations Squad, including Gunther. Him and the squad eventually warmed up to Eren and showed that he should trust them.