Maru traverses the desolate ruins of a shattered Tokyo alongside his resourceful bodyguard Kiruko, searching for a legendary "Heaven" that promises salvation from a world overrun by horrific, supernatural beings. While their external hell-scape is almost entirely void of anything mechanical, a hidden sanctuary exists within high walls where youths are raised in a nursery-style setting by robots. These sheltered children are full of potential and curiosity, yet Maru and Kiruko must face the brutal reality of a landscape inhabited by bizarre and powerful monsters known as Man-Eaters. This startling duality forces the young survivor to confront the terrifying possibility that the paradise he seeks is more of an untenable dream than a potential reality. Driven by hope and an unwavering goal, Maru continues his perilous journey to uncover if "Heaven" truly exists or if the walls are merely hiding another nightmare.