When grey mist engulfs the continent, the sacred Ash Wall becomes humanity's last refuge, ruled by an archbishop who sacrifices the weak and dissenters to the mist under the guise of purification. Framed and cast into the grey mist in his past life, Kai is reborn with mist‑resistant powers and infiltrates the wall. He uncovers the archbishop’s scheme of profiting from public fear and extending his life via sacrifices. Allying with common folk, doubting priests and outcast infected survivors, Kai gathers evidence against the church. While fending off mist‑twisted monsters assaulting the barrier, he dismantles the false theocracy and tears down its brutal sacrificial system.
