|Former Affiliation||104th Trainee Corps.|
|Manga||Chapter 1- To You, 2000 Years From Now|
|Anime||Episode 1- To You, in 2000 Years|
|Anime||Kishō Taniyama (Japanese) Mike McFarland (English)|
Jean is slightly taller than Eren with gray hair. He is often described as having somewhat of a horse face.
As part of the 104th, he ranked in the top ten of its graduates, placing just under Eren Jaeger and coming in at sixth.
After the second attack of the Colossal Titan, he, like many others, was eventually sent to the front to deal with the titans that had entered the city. However, due to the supply shortage, he was unable to fight at first. With the arrival of Mikasa, he and the rest of the group rush towards the HQ to resupply. When Mikasa runs out of gas, he takes the lead. When another soldier runs out of fuel, he takes advantage of the distracted titans and orders the remainder to finish the remainder of the trip. He second guesses this decision when he realizes that he and the group only made it because he took advantage of the deaths of his teammates.
When he sees the resupply team, he strikes one in anger, telling them they are responsible for the soldiers being killed. Soon after, Mikasa, Armin and Conny arrived with the help of the rogue titan. Still having to deal with the titans in the headquarters, he was in the second group in Armin's plan to clear the supply room.
After resupplying, he stayed back with Reiner and Annie. After Reiner suggested helping the rogue titan out, Jean was hesitant, as they had just barely escaped with their lives and he was unwilling to risk it again for a titan. Fortunately, they didn't have to, when the titan broke itself free in order to attack another titan, collapsing soon after. He ended up being one of the first people to know about Eren's titan transformation, when he emerged from the fallen rogue titan.
It was revealed that during another altercation, Eren upon learning that Jean's behavior was similar to his own at one point, learns to control his emotions as a soldier. After learning one of Annie's techniques in hand-to-hand combat, he uses it on Jean after confronting him for his beliefs. 
After finding the body of his friend, Marco, Jean is clearly disturbed. Later after remembering Eren's confrontation, and Marco's compliment about his mental strength; against his own wishes and his fear, Jean joins the Scouting Legion instead of the Military Police.
He was later chosen to pose as Eren because both have similar bad attitudes and eyes. 
At Eren's bedside, Jean finally learns about Annie being the Female Titan from Armin and she's encased in a crystal to avoid interrogation. He also finds out that about the titans similar to the Colossal Titan inside the Walls being used due to their hardening abilities. Jean and Armin heads down to the meeting between Commander Erwin Smith and the head of the Military Police.
When Jean reappears and is outraged when he learns of Reiner and Berthold's betrayal and their secret correspondence with Annie. He also learns about Ymir being a titan shifter and that both she and Eren are taken hostage. Outraged and determined to stop his traitorous teammates, Jean readily takes his stance with the Scouting Legion, Military Police and Stationary Guard. 
Jean Kirstein's Statistics:
- Eren Jaeger - Eren and Jean share a very pronounced rivalry. Eren finds Jean's initial goal of living a safe, privileged life in the police force to be cowardly and disgusting. Jean on the other hand, finds Eren's eagerness to join the "suicidal" Scouting Legion to be idiotic. Though the two often engage in fist fights, they could also be considered friends of sorts.
- Mikasa Ackerman – Jean had/has a slight crush on Mikasa
- Marco Bott - They were best friends and ultimately led him to joining the survey Corps when he said "I don't want those charred bones to be disappointed in me." after Marco died jean kept one of his teeth.
- Armin Arlert- The boy who's saved him twice, also known as his boyfriend.