M3: Sono Kuroki Hagane

In the Lightless Realm—a pitch-black void beyond their world—a group of children once found each other and formed a bond before being torn away and sent back to their own dimension. Years later, they reunite as the Lightless Realm begins to spread, unleashing creatures called Admonitions. Piloting mecha known as Vess, they can only hold the line, slowing the void’s steady encroachment rather than stopping it.

The fragile balance shatters with the emergence of a new threat: a “Corpse,” linked to a haunting melody said to kill anyone who hears it within nine days. After the group is exposed to the so-called Corpse Song, fractures deepen as each member retreats into personal turmoil—putting their unity, and humanity’s chances of survival, at risk.