Summary
Siss serves as a soldier in the Scouting Legion and is part of the unit dispatched for the 57th expedition. His debut occurs during the mission launched from the Karanese District into the territories beyond Wall Rose, which are overrun by Titans. In a battlefield environment where the 3D Maneuver Gear is ineffective, he collaborates with Ness to eliminate a rogue Titan. The pair coordinates their efforts by having Ness sever the Titan's ankles, causing it to fall, which allows Siss to deliver the fatal blow by destroying the nape of its neck.
