It is thirty years after the failure of the Space Colonization Program. Humanity is nearly extinct. A perpetual and deadly Rain falls on the Earth. Men known as "Junkers" plunder goods and artifacts from the ruins of civilization. One such Junker sneaks alone into the most dangerous of all ruins—a "Sarcophagus City." In the center of this dead city, he discovers a pre-War planetarium. And as he enters he is greeted by Hoshino Yumemi, a companion robot. Without a single shred of doubt, she assumes he is the first customer she's had in 30 years. She attempts to show him the stars at once, but the planetarium projector is broken. Unable to make heads or tails of her conversation, he ends up agreeing to try and repair the projector...

[Source: Steam]

Film adaptation of a side story of the Planetarian visual novel.

An adaptation of the visual-novel by Key, Planetarian: Hoshi no Hito combines the story of the original work with an expansion that extends the narrative with content from the Hoshi no Hito light-novel sequel.

In the future after much of the world has been devastated by nuclear and biological warfare, a young scavenger or "Junker" exploring a quarantined and abandoned city comes across a service robot still faithfully awaiting customers in the rooftop planetarium of a department store. Against his pragmatic instincts he helps the robot repair the planetarium's projector: a decision which will change both their fates.

[Source: Anime News Network]

――This is the story of a small miracle.
Stars from different universes and different times that were never meant to cross paths. By irony of fate, these stars come together in “Kaginado Academy”.
What awaits them there is a lively school life full of hope and dreams.
The wonderful encounters provide the stars with new radiance.
What awaits beyond that radiance...?

[Source: official website]