Keiji is a tall, tan soldier with a large build. He has brown hair, which is beginning to turn gray in the back, which he keeps in a buzz cut, brown eyes, and has rather defined cheekbones. During missions, he is shown wearing the standard Scout Regiment uniform.
Keiji is first seen participating in the operation to capture the Female Titan inside the Forest of Giant Trees during the 57th Exterior Scouting Mission. Commander Erwin Smith calls him to prepare the explosives to to blow off the Female Titan's hands, which are protecting its nape. Keiji expresses concern that doing so would also blow up whoever is inside. Erwin takes his input into account and modifies the order to amputate the wrists instead.
They stop in Ehrmich District where Hange goes over a report about Annie Leonhart's background with a number of Scouts, including Keiji. He hears Armin, Eren, and other members of the 104th discuss whether it is possible that Reiner Braun and Bertholdt Hoover could have been working with Annie.
Keiji is among the soldiers that accompany Hange Zoë to rescue the 104th cadets trapped at Utgard Castle. When, during the battle, Eren ignores orders to stay out of sight in favor of killing his first Titan in his human form, Keiji berates him for breaking cover.
After rescuing the recruits at Utgard Castle, Keiji returns to Wall Rose with the rest of Hange's squad. As the heavily injured Ymir is being lifted to the top of Rose, Keiji muses that, had she been a normal human, she would not have survived her experience at Utgard. After Hannes brings word that there is no hole inside of Wall Rose, the soldier prepare to return to Trost District, but are stopped when Bertholdt and Reiner reveal themselves to be the Colossal and Armored Titans.
Keiji and the other Scouts scatter to avoid the Colossal Titan's attack, but he notices that one of the soldiers does not make it and is captured by Bertholdt. To his surprise the Colossal Titan eats both the soldier and Ymir. Hange orders her soldiers to swarm the Titan. As they dodge around its fist, Keiji notices that the Colossal Titan is slow, just like in the reports. He joins the other soldiers in diving for its nape, but before they can reach it, the Colossal Titan emits a scalding burst of steam that drives all of them back.
Hange leaves three of the four squads present to watch Bertholdt and takes the remaining squad, including Keiji, to face the Armored Titan, which is fighting Eren in his Titan form. Eventually Eren gains the upper hand and traps the Armored Titan in a hold that threatens to tear its head off. Keiji hangs off the Wall with the other soldiers and shouts encouragement to Eren.
The Armored Titan roars in desperation and the Colossal Titan responds to the signal. It plunges from the top of the Wall to land on Reiner and Eren, creating an explosion of steam. Keiji is burned by the scalding winds and is laid out among the unconscious wounded on top of Wall Rose.
- Although Keiji is portrayed simply with brown hair in the anime, streaks of gray were added in the second anime recap movie to better match his appearance in the manga.
- This change was retained in the second season of the anime, in which Keiji again appears with graying hair.