On December 20th, 198X, people around the world mysteriously experience the same dark dream. Shortly thereafter, the number of humans who cannot wake from their sleep begins to rise steadily. Reports emerge of collective, life-like "R-dreams" haunted by "Zel," creatures of nightmare. Hokuto, an art student struggling to make ends meet, remains skeptical of R-dreams until he is drawn into one himself. Inside, he makes new friends, fights the Zel, and attempts to comprehend the nature of this perilous phenomenon.