In the pitch-black void known as the Lightless Realm, a group of youths become fast friends. Sadly, they are later separated and whisked back to their own dimension. After years apart, they reunite to combat the Admonitions, frightening creatures that hail from the same realm. The five friends harness Vess robots to stem the expansion of the Lightless Realm, but it seems their efforts are in vain. Suddenly, their existence is upended by a new foe, the Corpse. This strange entity's eerie melody supposedly leads to death within nine days of exposure. After hearing the Corpse Song, the gang faces strife and drifts apart, each one plagued by individual troubles that endanger the future of humankind.