Jujutsu Kaisen explored Maki and Mai's emotional original story as part of the Zenin family! When Mai was first introduced to the anime in the debut season's first half last Fall, she had seemingly been carrying a major chip on her shoulder. This was later confirmed to be because of her older sister, Maki, who is fighting to become a Jujutsu Sorcerer in her own right before her family had disowned her. With the newest episode bringing these two sister to blows with one another at last, it took the time to dive into their complicated origin story.
Episode 17 of Jujutsu Kaisen's anime continues the fights between the Tokyo and Kyoto Jujutsu Tech schools, and Maki and Mai use this time to air out their respective grievances with one another. It's here we learn about how Maki's determination and lack of cursed power eventually lead to a rougher future for Mail, and that's why she's come to harbor so many negative feelings for her sister.
The episode confirms that Maki Zenin was born without cursed energy, but due to a special contract that she received upon birth, she was gifted with phenomenal strength. But due to the Zenin family's upholding tradition and refusal to acknowledge any kind of weakness, Maki has since been disowned and her family continues to make sure that she cannot progress in her Jujutsu Sorceror career.
This made the young Maki fight even harder as a result, and she made a direct vow to become the head of the Zenin family and essentially shows that she left to become a Jujutsu Sorcerer of her own volition. This created some complicated feelings for her little sister, who was forced into a life of a Jujutsu Sorcerer that she didn't want. She didn't want to fight monsters that she feared, but only had to do so because of Maki's actions.
The two sisters were close at a young age, but since then these complicated emotions have flourished into an even more complicated anger and resentment. Although it's mostly from Mai's end, it seems like Maki's harboring her own feelings as well that came out through the fight. But what did you think of this look into their back story? Let us know your thoughts in the comments or you can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!