Masamichi Yaga/Synopsis

History
At some point in the past, Masamichi became the principal and second-year teacher of the Tokyo college. Masamichi had also created Panda, and trained him. Masamichi also explained to Panda that he has an older brother and sister.

After the creation of Panda, Yaga is taken into a cell with his hands bound by seals. He is talking to Yoshinobu Gakuganji about Panda. Gakuganji wants to know how Panda was created, as he works differently from other cursed corpses by having his own cursed energy. Gakuganji believes that Yaga could pose a major threat to society if he was able to create a cursed corpses army that's similar to Panda. Yaga assures Gakuganji that he doesn't know how Panda was made.

At some point, Masamichi created a cursed corpse with Atsuya Kusakabe's nephews information. He is with Takeru when Atsuya brings his sister along who rushes to hugs Takeru the moment he says "aren't I a genius". Kusakabe tells Masamichi that he is truly grateful.

Gojo's Past Arc
Eleven years ago, Masamichi punishes Gojo for not putting up a curtain when Gojo along with Geto and Shoko check up on Utahime Iori and Mei Mei. Later Masamichi meets with Gojo and Geto, where he gives them a mission from Tengen. Masamichi informs the two about the importance of the mission, and that there will be two group that they will have to look out for. Later, Masamichi is contacted by Gojo about their circumstance which he tells them to follow Riko Amanai's request since this is Tengen's orders.

A year later, Masamichi informs Gojo about how Geto had massacred an entire village and is currently on the run. Masamichi also informs Gojo that Geto had also most likely has killed his own parents after going on the run. Later, Masamichi meets with Gojo after Gojo has met with Geto.

Cursed Child Arc
Masamichi meets with Gojo, and talks about how they have to locate Geto. When Geto suddenly shows up at the college for Yuta Okkotsu, Masamichi along with several other sorcerers go to confront Geto. After Geto makes his proclamation about an all-out war and leaves, Masamichi attends a meeting where they discuss their course of action.

Fearsome Womb Arc
Masamichi meets with Gojo and Yuji Itadori for an interview to see if Yuji will attend the school. When Gojo and Yuji arrive at the meeting place, Masamichi says that they are late. When Yuji introduces himself, Masamichi asks him why he is here. Yuji says that he is here to help people because it was the last request from his grandfather, Masamichi doesn't like his response and says that he is disqualified. Masamichi then has more of his corpse dolls attack Yuji and explains what it is and that it will continue to attack until Yuji gives him an answer he likes.

As Yuji is continued to be attacked by the doll and tries to to give another reason, Masamichi explains what a sorcerer does and how most of them die. When Yuji says that he will never regret how he lives, Masamichi accepts this answer and welcomes Yuji to the school. However, he forgets to deactivate his technique.

Days later Masamichi goes to meet with Gojo, but notices that Gojo is late. The next day, Masamichi is to attend a meeting with the Kyoto college principal, Yoshinobu Gakuganji, but is told by Gojo the wrong time of the meeting.

Kyoto Goodwill Event Arc
On the day of the Kyoto Goodwill Event, Masamichi is with Yoshinobu when Gojo reveals that Sukuna's host, Yuji, is still alive. Masamichi then explains the rules of the event along with Gojo, while punishing Gojo.

When the event starts, Masamichi is with the other faculty watching the event through monitors. When intruders invade the site, Masamichi heads over to go find Tengen. After the intruders have been dealt with, Masamichi attends a meeting with the other faculty and informed of the casualties and what was stolen from the invasion. After they all discussed about how they should keep what was stolen a secret from the higher-ups, Masamichi suggest that the Kyoto Goodwill Event be over.

After it is decided that the event will continue, Masamichi is surprised that the next day event is baseball. Masamichi then watches the game along with Yoshinobu. During the game, Masamichi talks with Yoshinobu about Yuji.

Shibuya Incident Arc
On October 31, Masamichi has Shoko set up a tent near Shibuya, to help out the wounded sorcerers. As Shoko tells him that she doesn't need him to be around, but Masamichi explains how they need to protect Shoko since she is the only one that can use the reverse technique. When Megumi Fushiguro shows up, Masamichi is surprised by this and wonders about how he thought he saw either Yuji or Sukuna.

Itadori's Extermination Arc
In the aftermath of the incident, Masamichi has been given the death penalty for inciting his former students, Satoru Gojo and Suguru Geto, the latter whose revival has been confirmed.

Perfect Preparation Arc
In a flashback, Masamichi was seen talking to Takeru while hiding in the forest, telling him that he won't be coming back for a while and telling him that his mother would come and get him. Masamichi is then seen alone walking along a street when a jujutsu higher-up suddenly appears atop a light pole and confronts him, asking where he's going without any cursed corpses. Masamichi tells them that he's going to say goodbye to his son, the higher-up tells him the only other way to save himself is to tell them how to make independent cursed corpses where he comes to the conclusion that the jujutsu higher-ups became more pushy the moment Satoru Gojo was sealed. The higher-up confirms this before saying that they are after all, a veteran sorcerer, just then principal Gakuganji appears and the two gets into a fight with Masamichi being defeated and heavily wounded.

Masamichi then tells Gakuganji that one can replicate a souls information from physical information and that information has to be placed into a cursed corpse's core. Three highly compatible cores that are constantly observing each other must then be placed into a corpse and only then will the souls stabilize and give rise to self-awareness, three months are then required for the cursed corpse to reach self sustaining cursed energy. Gakuganji then asks Masamichi why he didn't reveal this information before he was fatally wounded and Masamichi replies that this was a curse from him to Gakuganji. Panda then arrives and Gakuganji prepares for a fight but Panda ignores him and rushes to Masamichi's side, cradling his body.

Shinjuku Showdown Arc
As Gojo dies after his fight with Sukuna, he has a conversation with his deceased allies in the afterlife where Masamichi is present. After that Gojo turns to him and asks him about how there was no such thing as sorcerer dying without any regrets while Masamichi covers his ear in annoyance.