Ajin: Demi-Human is a dark, high-tension supernatural thriller manga that explores immortality, fear, and moral collapse in modern society, following Kei Nagai, a coldly rational high school student who discovers he is an Ajin—an immortal being hunted, experimented on, and feared by humanity—after surviving a fatal accident, plunging him into a brutal conflict between governments, civilians, and terrorists led by the charismatic and terrifying Sato, where death has no meaning and violence escalates without restraint, delivering relentless action, strategic warfare, and psychological mind games while questioning the value of life, ethics of experimentation, and how society treats those deemed “other,” distinguished by its grounded tone, realistic tactics, and unsettling atmosphere that strip away traditional heroism in favor of survival and ideology, making it one of the most intense and mature modern seinen manga with strong appeal beyond typical supernatural stories, also known as Ajin manga, Ajin Demi Human, Ajin Demi-Human manga, 亜人, Ajin Seinen manga, immortal humans manga, Sato Ajin manga, and dark supernatural thriller manga.