JeanKasa

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

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

After Mikasa's ribs were crushed by a titan, Jean was infuriated and stabbed the titan in the eye, freeing Mikasa and saving her life.

When Jean was disarmed and about to be shot, Mikasa rushed to try and save him. However, it was Armin who ended up saving him.

Mikasa was shown treating Jean's wounds during the mission to retake Wall Maria.

Fanon
Considering recent developments in the manga showing everyone, including Mikasa, to have lost faith in Eren, it is possible she will not love Eren forever and fall for someone else instead. This could be Jean given the fact that they have spent four years in close proximity with each other.

Fandom
AO3