A cleanly shaved head and an easy-going charisma, Conny wears the same uniform as the boys in Titan Junior High School.
A carefree Conny makes his way to school but comes across Eren and Mikasa colliding into each other. He then ignores it and continues on with his day. Thereafter, Conny finally reaches Attack Junior High School and runs to class realizing that he is late. He unknowingly runs to the Titan side of Titan Junior High and enters Titan class 1-4. There he is attacked by falling stationery and tumbles out of the classroom. He is found by Hannes who directs him to his classroom. There, Conny introduces himself stating that he is from Wall Rose South District Ragako Elementary school while saluting with the wrong hand. He is given a noogie by his homeroom teacher. Afterward, he attends the entrance ceremony and has his lunch eaten by a Titan.
Conny wonders why the person sitting next to Eren has been absent for a long period of time. That turns out to be Armin, who is properly introduced to him later. Conny follows his friends to find the Attack Junior High Scout Regiment, where he is accepted into said unauthorized club. The next day, his name is signed up for the Wall Cleanup Club because of the unauthorization of the Scout Regiment.
Conny participates in a game of dodgeball. However, he struggles to remember the rules and has Marco teach him throughout the game until he understands. In the last minute, his team wins due to Conny's throw, sending Annie out.
Walking towards the Wall Cleanup Club, Conny comments his make-believe "Going-home Club" as Eren suggests that it would be as secretive as the unauthorized Scout Regiment. With that said, he finds himself mumbling about his imaginary club instead of cleaning the windows under the orders of Rico Brzenska. After Jean is caught slacking off, Conny and the others are introduced to the club's secret weapon, the omni-directional mobility gear.
He goes to comply with the activity the president has assigned them. Upon gaining Rico's appreciation, he goes to train with the rest.
Along with Sasha and Jean, Conny freely maneuvers his gear with ease. With the next day on Eren's finally successive move, he along with the group hide behind trees as a bunch of Titans are horrifically graffiting the Walls. As Rico explains, Conny learns about the sole purpose of the Wall Cleanup Club.
In the test results day, Conny fails at his tests and cheerfully accepts Armin's help in studying for the makeup test but eventually forgets about it and goes home. He forgets about the day of the makeup test as well and is automatically put in refresher classes.
At the end of the day, Conny tells Sasha about a ramen restaurant, which makes her drool. In the next day, Conny remarks how women are scary when Annie and Mikasa confront each other. Later when Jean's love letter turns out to be from a Titan, Conny teases him about going out with the Titan.
Conny wonders how much the upperclassmen love bread when Jean mentions Year 1 students are forbidden from buying it at the school shop. Conny and the others arrive late at the Scouts club due to cleaning every window in school by Rico's orders. The upperclassmen chastise the group and start nitpicking over their appearances, except for Conny who is happy for having a close-cropped head after Gunther mentions guys' hair should be the same as his. After Levi gives the group a challenge, Conny participates in the school's Sports Day and remarks how scary the upperclassmen are when they beat up Jean in the second game.
The upperclassmen plan a sudden "Test of Courage" event at night. Conny is assigned to Eren's group and they head to the art room first. They hear a disembodied laugh from a painting. They all flee from the room after the painting's face morphs, giving a sinister grin. Arriving at the music room, the group suddenly hears the piano playing by a figure, with Mikasa translating what Armin murmurs about the ghost. After Eren runs off on his own, they regroup with him on a stairwell and when Mikasa again translates what Armin murmurs about a cursed mirror after Eren starts screaming about it, Conny is impressed by her ability to tell what Armin is saying. At the gym, everyone starts running around as ghosts and a giant cannon appear chasing after them. It is later revealed that the event is a prank played by the upperclassmen.
In class, Conny bets the weather being sunny for tomorrow based on one of Bertholdt's odd sleeping positions. He later goes to the summer festival with his friends. When he and Sasha head to buy shaved ice for the group, they take too long returning, resulting in the ice melting. He later participates in die-cutting with the others and watches as more festival fireworks are set into the sky.
Following an election for a new student council president, Conny joins the pursuit when the candidates start chasing after a notebook that allegedly contains info which could help them win the election. Conny intercepts Jean, before he in turn is intercepted by Sasha who momentarily takes a look inside. Conny asks her and she reveals that the school gets more yakisoba bread on Wednesdays, to his surprise.
In the school's 104th festival, Conny participates in a Snow White play as one of the dwarfs. When Jean is forced to take Armin's role as Snow White due to him being occupied by Eren's chee-burgs stand, Conny mentions how unfair that Jean gets to just lie down on stage and do nothing. He then teases Jean by saying he looks super creepy as Snow White, much to his annoyance.
Conny joins Eren and the others in pursuing their stolen chee-burgs from the Titans' building. After being rescued by Hannes, he points them to the principal's office and in there, Eren opens up a door using a key. The Colossal Titan then lifts the roof and eats the chee-burgs stand along with Eren, but later spits him out and Eren reveals a chee-burg he retrieved, with Conny celebrating their victory.
- Sasha Braus - Conny and Sasha have a lot in common, as such it is natural that they get along; their personalities make it so that they find the enjoyment in everyday things. They appear to enjoy each other's company as friends.
- Conny's name may have multiple meanings, either from the Celtic name "Connor," meaning "son of the wolf," or "Constantia," meaning "conviction." "Springer" is German for "knight," "leaper," and "dolphin."
- Conny cuts his own hair.