Beirer had pale skin and short brown hair which he kept combed back out of his eyes. During missions, he wore the standard Scout Regiment uniform.
Beirer was a trusted member of the Scout Regiment, being given positions of command when Erwin was not present. He could also often be seen personally escorting and assisting Erwin on scouting missions. He also seemed to be quite brave.
Beirer is one of the Scouts assigned to patrol the inside of Wall Rose for Titans after reports are received that the wall has been breached. After returning from his duties, Beirer informs a perplexed Jean Kirschtein that no Titans were discovered inside the wall.
Beirer is among the Scout Regiment soldiers who participate in the mission to rescue Eren Jaeger from Bertholdt Hoover and Reiner Braun with Military Police Regiment and Hannes Unit from Garrison Regiment. When noticing the red smoke shooting in the air, Beirer reports the sighting to Erwin.
As Erwin leads the amassed soldiers in a charge against Reiner and Bertholdt he is attacked by a Titan, being knocked from his horse and losing his arm. Beirer attempts to run to the commander's aid but is eaten by a Titan while en route.