Like Maki, Mai was mistreated by the Zenin Clan growing up only for being a girl with little talent for jujutsu. While Mai was begrudgingly willing with living under their thumb as a servant and would rather do chores than fight, Maki wanted to spite the clan and work as a sorcerer. The repercussions of Maki's rebellion forced Mai to study to become a jujutsu sorcerer. Mai detested the grotesque work exorcising curses entails and resented Maki for essentially thrusting them both into that life. Mai was an unwilling sorcerer who took out her frustrations on others, mainly her rivals and her twin sister. She had a snarky and rude personality due to her experiences. She is crude and liked to boost her own ego. While Mai didn't particularly like Aoi Todo, she appeared to be the only one who could tolerate Todo and would hang around him to make herself look tougher than she is. Unlike how she treated the Tokyo students, Mai got along with her peers, for the most part, especially the girls Momo Nishimiya and Kasumi Miwa. She was visibly disappointed with Mechamaru when he betrayed their group.Although Mai was well aware of how physically gifted Maki is, she acted as if her twin sister is completely talentless. Mai barbed her directly during the lead-up to the Goodwill Event and targeted her juniors as well. Mai insulted Yuji Itadori, the dear friend of Megumi Fushiguro and Nobara Kugisaki who had recently died, just to taunt the first years upon meeting them.She also told Maki that she was worthless because she couldn't even use cursed energy.It is later revealed that Maki promised she would stay with Mai when they were younger. When Maki left the clan and broke that promise, Mai began calling her a liar. She hated her sister for leaving and never told her anything like her first crush or that she had a cursed technique. When Mai lost to Maki in the Goodwill Event, she asked why her sister didn't fall down the hole with her. She was dissatisfied with Maki's answer and continued to hate her from that point. Mai was forced to put her feelings toward Maki aside when their own father attacked them. With both twins sisters on the edge of death, Mai decided to sacrifice her life to give Maki the tools to live on. Mai always knew Maki was tough and acknowledged that she was only holding her sister back, openly admitting that the situation sucked. Mai suspected that she might have to make a tough decision one day and decided to go through with sacrificing herself so that Maki could reach her full potential. In a moment that took the twins back to their childhood, Mai asked her big sister to destroy everything in exchange. "Please, destroy... Everything. And I mean everything, big sis."