M3: Sono Kuroki Hagane

The Lightless Realm is a void that exists outside the children's world, where they once briefly interacted before being separated. Years later, they reunite to fight Admonitions, creatures born from this void, using mechs called Vess. However, their efforts can only slow the Lightless Realm's encroachment into their world. The introduction of a Corpse, whose deadly song is heard by the group, sets off a chain of personal struggles that imperils humanity's survival.