After six months, Ikoma and Mumei journey to the Iron Fortress and then to Unato, a devastated region overrun by the deadly Kabane. Amidst the chaos of this battleground, they face a new breed of Kabane with unexpected attack strategies. Teaming up with a local survival group, the Iron Fortress crew embarks on a mission to reclaim the territory. As they delve deeper into the castle's domain, they unravel the mystery surrounding these evolved Kabane, only to confront horrifying truths beyond their imagination. The alliance grapples with the grim reality of the Kabane, shedding light on the deep-seated despair lurking within Unato.