Luke had chin-length, straight brown hair tied back in a ponytail and hazel eyes. He wore the typical Scout Regiment uniform.
During the 57th Exterior Scouting Mission, Cis works with Ness to take down an Abnormal Titan. Ness takes out the Titan's ankles and Cis skillfully destroys the Titan's nape as it falls. Almost immediately after, another Titan appears. Following Ness' lead again, Cis tries to strike at the Titan, but it intercepts and crushes him effortlessly.
During the Battle of Shiganshina, as Erwin Smith begins to lament the dwindling hopes of his dream, Cis stands among the many fallen Scout Regiment comrades in Erwin's mind, wanting to know if their deaths had meaning.