Those Left Behind

After a young woman was transported to another universe, one of science fantasy, in order to defeat an existential threat known as the "demons." She did her duty, blessed by all the powers of this new universe and not only defeated the greatest threat, but was also responsible for the reconstruction of the systems in place before she was allowed to go home. Now, after she is gone, the system she had created is falling apart at the seams, as the existential threat is gone, as well as the absolute power of the hero. As things get worse, those who remember her well are required to either patch up the cracks, or shatter it entirely to create a new and brighter future.