Sorcerer Family/Zenin Family

The Zenin Family is one of the Big Three Sorcerer Families. Naobito Zenin was the head of the family until he died of injuries he sustained during the Shibuya Incident. In accordance with a special clause in Naobito's will, Megumi Fushiguro was named head of the clan instead of Naoya Zenin.

History
The history of the Zenin Family embodies the problematic values that arose from the nobility status granted to them as a major clan. The Zenin Family values powerful cursed techniques above all else and reject their own family members if they don't deem their power acceptable. Even Toji Zenin, as powerful a fighter as he was, found himself rejected by them due to his lack of cursed energy and left the clan, even changing his surname.

In a similar situation, Maki Zenin also left the clan to become a sorcerer in order to spite the other members. The Zenin Family still actively tries to prevent Maki from receiving a promotion in her sorcerer rank. Maki's twin sister Mai Zenin was also ostracized by the family despite possessing a technique and still being an active member. However, Mai is a girl, so "perfection" is expected of her unlike the male members of the family.

Toji's son, born Megumi Fushiguro rather than Zenin, was initially raised outside the clan, but the Zenin Family was willing to pay top dollar to reintroduce him back to the clan. Megumi was born with the Zenin Family's celebrated hereditary Ten Shadows Technique. Under the protection of Satoru Gojo, Megumi was brought into the clan and eventually made his way to becoming a student at Tokyo Jujutsu High. Megumi claims to have no connection with the Zenin Family any longer.

Itadori's Extermination Arc
Naobito Zenin was the most recent head of the Zenin Family before the events of Shibuya. He embodied the aforementioned ideals of the family in addition to its long-standing dislike for the Gojo Family. In his will, Naobito left everything to his son Naoya, who much like himself, embodies the problematic traditions of the major clans. Eager to become the head of the family, Naoya openly welcomed his own father's death. However, in Naobito's will, there is a clause that states if Satoru Gojo is incapacitated for any reason then Megumi is to become the heir. Trapped in a struggle for political power, Naoya didn't hesitate on his decision to kill Megumi.

Culling Game Arc
Megumi learned about inheriting the Zenin Family's assets from Maki. Naturally, Megumi had no interest in being a member of the clan at all, let alone its head so he refused. He was prepared to step down so Maki could enter the role but she knew no one would accept her. Maki was very stern with him, pointing out he possesses the clan's inherited technique and Satoru favored him. Maki believed she wasn't good enough because she couldn't make the clan a place where Mai could belong. Understanding Maki's feelings, Megumi reluctantly accepted his new role.

Even Jinichi agreed that Megumi is better suited for the role than Naoya. Many of the clan's members would like to repair their relationship with the Gojo Family. Additionally, Megumi is friends with Noritoshi, the next head of the Kamo Family. Naoya's reckless idea of assassinating him would hurt the clan's standing among the Big Three Sorcerer Families.

Following their meeting with Master Tengen, Megumi gave Maki official permission to enter the clan's cursed warehouse. She used the key to enter the storeroom full of cursed tools only to find her father Ogi inside. Having foreseen Maki's plan, Ogi removed all the cursed tools and injured Mai to use as a hostage. Ogi and Jinichi came up with a more organized plan for getting rid of Megumi. Although he's a better fit than Naoya, they refuse to hand over the family's fortune and assets to him. Their plan was to execute Megumi, Maki, and Mai for plotting to free Satoru.

Ogi overpowered Maki in their initial exchange of blows. He brought both twins to a place filled with grade 2 and lower curses meant for training and discipline. Ogi left his own daughter's behind expecting the cursed spirits to claim their lives. However, Mai sacrificed herself to give Maki a new weapon and took all of their joined cursed energy with her. In exchange, Mai asked that Maki destroy everything.

Maki exorcised all the curses in seconds and confronted her father again immediately after. Her newfound strength frightened Ogi, reminding him of Toji. He was the first to be cut down on Maki's avenging rampage for her sister. The clan's alarm was rung after Ogi's death and the majority of the sorcerers at the household immediately went to deal with Maki.

Nobuaki and the Kukuru Unit attempted to subdue her first but Maki slaughtered the minor members of the squad. The Hei joined the battle to kill Maki but each of them fell one by one to her newfound prowess as well, leaving only Naoya.