Mahito

Mahito is a curse given shape by human malice, a stitched, patchwork figure who studies people the way a child studies insects. He talks in soft, reasonable tones about the meaninglessness of human life, and treats his ability to reshape souls as a curiosity to be tested rather than a weapon to be feared.

The writing makes his horror conversational — he never raises his voice, because he doesn't need to, and that calm is scarier than rage would be. Shimazaki gives him an unhurried, almost delighted lilt, so every soft-spoken question lands like a threat. He's a monster who genuinely wants to understand you before he ruins you.