In the realm of Mushrambo, humanity has nearly vanished. After a lethal virus drove mankind to the brink of extinction, a new species known as the Enterrans was crafted to sustain life on Earth. But peace between the Enterrans and their human creators did not endure. A conflict erupted, pitting the Enterrans against humans and their mechanical allies. The Enterrans emerged victorious, renaming Earth as Enterra in celebration of their triumph.
Before humanity's final collapse, one of the last scientists sealed his daughter, Yakumo Shindou, inside a cryogenic chamber. His hope was that she would eventually awaken and discover the human refuge called Shinzo, thereby reviving humanity and bringing harmony back between humans and Enterrans. Centuries after the war, Yakumo stirs from her slumber and meets an Enterran named Mashura, who vows to aid her journey. Joined by fellow Enterrans Sago and Kutal, the group must track down Yakumo's missing memories and locate Shinzo. Yet not all Enterrans are friendly; some will stop at nothing to ensure humanity never returns.