Seok-min, a perennial job seeker, is being forced by his parents to do something about it after reducing the financial support they have been providing to him to a few dozen dollar a month. In despair, he decides to while the time away in a nearby park. There, he notices Na-eun, a charming and quirky young woman sporting a helmet adorned with a spoon who spends her time sitting there, trying to communicate with aliens. After much difficulty trying to connect with her, he finally gets her to not use pepper spray against him and tell her story. Na-eun would want him to believe that she comes from a distant star in the universe and that she is bound to return to her celestial home. Infatuated with her, Seok-min believes in her unconventional tale, having himself experienced an encounter of the third kind when he was a child, and offers his help. As they gradually grow closer, Seok-min realizes that he is not willing to let her return to the stars.   

The film not only marks Koo Sang-beom's entry into feature filmmaking but is also a heartwarming and uplifting movie that embraces what Gu coined as the "escape Earth romance” genre. As the two protagonists cautiously approach each other and open their hearts, showing that their worries and issues are not so “alien” to us, the narrative delves into more profound issues that will resonate with younger generations as we discover the characters’ past. Gu wanted She's from Another Planet to provide as much solace as inspiration and hope for a more compassionate and peaceful world. Lead actor Baek Seo-bin could be seen in The Policeman’s Lineage, while his female counterpart Shin Yeon-suh was first known as a member of K-pop girl band Gugudan and has since been pursuing an acting career, mainly on television.