Naoya Zen'in

Naoya Zen'in is the golden boy of one of jujutsu sorcery's great families, and he never lets anyone forget it. Contemptuous of relatives without inherited cursed techniques, he singles out his cousin Maki for special cruelty, treating her strength as an insult to the bloodline he worships. Charming to those who matter, vicious to those who don't.

The show gives him real menace precisely because he isn't a cartoon bully — he's articulate, self-assured, and genuinely gifted, which makes his contempt land harder. Koji Yusa plays him with an easy, almost bored cruelty, never raising his voice, so the malice feels like a personality trait rather than a performance. You despise him efficiently.