Riko is one of the several remaining workers in the Archive Excavation Department. She is often absent from work due to slacking. She thinks digging up archives isn't going to change the world she dislikes for her grandmother died in there in grief of losing the 'green world of the surface'.

A future where the continuity of history has broken off, a world of enormous ruins that continues endlessly. Oceans and continents have vanished, existing only within the archives brought up from the remains. Ura works in the Archive Excavation Department, which restores and analyzes the data left behind. One day, he finds a disturbing visual record...
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(Source: Anime News Network)