After an event that leaves her traumatised, the nineteen year old Lethe suddenly finds herself stuck in the future - trapped in the body of her older self. As well as having to adapt to her new environment and deal with a figure that seems to be a twisted copy of her, Lethe also discovers that her life hasn't panned out the way she had planned: having had a son with whom she has a crumbling relationship. Despite all of the difficulties she encounters, the question arises that it might be better for Lethe to stay, after all, in this new world.