Franz had a large build with shaved black hair. He wore the standard trainee corps uniform.
He was a good-natured young man, only wanting everyone to get along. He was not one to get upset or anger others. But when there was a chance Hannah Diamant would be in danger, he vowed to protect her if it was the last thing he would do.
On the 104th Training Corps' last night together as trainees, a fight between Eren Yeager and Jean Kirstein breaks out. As the fight picks up, Mikasa Ackerman stops it by carrying Eren out of the mess hall. Franz also blocks Jean's path, nervously convincing him that the fight was over. Later that night, Franz helps carry Eren to his bed after he passes out.
The next day, Franz is walking through Trost District with Hannah and Eren. He and Hannah begin chatting, optimistic that things are looking up for humanity. Angered, Eren begins yelling at them, calling them a couple, embarrassing them.
After the Colossus Titan's attack on Trost, Hannah is frantic at the situation they are in. Franz tries to ease her fears, vowing to look after her no matter what.
Later, Armin comes across Hannah frantically trying to revive Franz's mutilated body with CPR.
- Franz's name is remarkably similar to Franz Kafka, a Czech writer considered to be one of the most influential authors of the 20th century. Franz's lover, Hannah Diamant, shares the same last name as Dora Diamant, who was the lover of Franz Kafka during the final year of his life.
- Franz shares a birthday with Mr. Arlert.