ItaJun

YuJun is the slash ship between Yuji Itadori and Junpei Yoshino from the Jujutsu Kaisen fandom.

Canon
The two met when Yuji was carrying out his first mission since his "death", they quickly became friends thanks to their common passion for movies (especially horror movies). Yuji met his new friend's mother and they in turn hit it off. Junpei had met Mahito, a curse (a sort of demon), who wanted to help him get revenge on those who harassed him. But Mahito was a heartless manipulator and made sure that Junpei's mother was killed so that Junpei would go directly to his stalkers with his newfound powers. Mahito then turned Junpei into a curse, killing him.

Fanon
This is quite rare ship given that Junpei only appeared during arc time and died but it left its mark on anime viewers and manga readers. Junpei is a fairly introverted teenager but quickly got on well with Yuji.

Fandom
YuJun posts on Tumblar