Dies irae begins in present-day Suwahara City, where a string of grisly decapitation murders unsettles everyday life. Ren Fujii is trying to regain his footing after a violent fight with his former best friend, Shirou Yusa, and his uneasy return to ordinary school life soon gives way to something far more disturbing when he starts dreaming of being condemned to death by guillotine. Those visions feel uncomfortably close to reality, and the killings spreading through the city make the boundary between nightmare and waking life harder to trust.
As the deaths continue, the people around Ren—including Kasumi Ayase and Rea Himuro—are drawn into a conflict that reaches far beyond the streets where the murders occur. Kei Sakurai, the enigmatic Marie, and other hidden players stand near the center of powers Ren does not yet understand. Loyalties shift, old wounds resurface, and buried history pushes into the present, linking Suwahara to a ritual carried out by Nazi officers in Berlin on May 1, 1945. School drama, occult action, and psychological horror collide as the city becomes the stage for personal grudges, supernatural forces, and impossible revelations. What starts as a mystery surrounding a killer evolves into a struggle over the powers shaping Ren’s world and the ties binding the key players together.
