Yu Haibara/Synopsis

Gojo's Past Arc
Yu and Nanami are called on to assist Geto and Gojo with protecting Riko while they are at Okinawa. Yu expresses his excitement about helping out Geto and Gojo, while Nanami voices his opinion about how this is not an appropriate mission for first years. Later, Yu informs Nanami about how they are going to stay in Okinawa for one more day.

A year later, Yu meets up with Geto and the two have a conversation. Geto suddenly asks Yu if he likes being a sorcerer, to which Yu answers that he likes when he does things that only he can do. When Yuki Tsukumo shows up, Yu leaves for a mission while leaving Geto and Yuki to talk alone. During the mission, Yu is killed and his body is taken to the college morgue.

Shibuya Incident Arc
Years later, when Kento Nanami was at death's door after being attacked by Jogo and about to be killed by the special grade curse, Mahito, he remembered Yu and asked him why he returned to being a jujutsu sorcerer. Yu then appears in a vision and points to Yuji Itadori as his answer.

Shinjuku Showdown Arc
Yu is present when Gojo talks to Geto and Nanami in the afterlife.