JeanKasa

JeanKasa is the het ship between Jean Kirstein and Mikasa Ackerman from the Attack on Titan fandom.

Canon
In the "sudden visitors" OVA, Jean is seen drawing a picture of a pretty girl under his blanket in his room whilst his mother is yelling at him from downstairs. He seems to be rushing it and the picture looks fairly like Mikasa.

Jean immediately develops a crush on Mikasa upon seeing her for the first time, causing him to blush and stutter. He finds her long black hair in particular to be very beautiful.

When Jean and the other cadets are stuck on the roof during the Trost Mission he remarks that it has been a dull life and laments over never having told 'her' how he felt.

Jean appears to be jealous of Eren whenever he is with Mikasa. When Mikasa stays with Eren while he is hurt and in bed, Jean is seen with a depressed face as he walks out the door.

After Mikasa's ribs are crushed by a titan, Jean becomes infuriated and stabs the titan in the eye, freeing Mikasa and saving her life.

When Jean is disarmed and about to be shot, Mikasa shouts his name and rushes to try and save him. However, it is Armin who ends up saving him.

Mikasa is shown treating Jean's wounds during the Battle of Shiganshina.

Fanon
The fandom has taken it to call Jean's drawing “Jeans Dream Girl” implying that Mikasa is the girl from the drawing, even though the two hadn't met yet.

Given that Eren is set to die in four years, it is possible that after his death Mikasa will fall for someone else. This could be Jean given the fact that they have spent four years in close proximity with each other.

Fandom
AO3