Takagi Haru was a normal university student with an abnormal passion for stargazing. His average life changed, however, when an alien princess from another planet crash-landed on the roof of his university at night and declared her love for him.
Haru thought that Ena and her wacky antics were all he had to deal with, but he then discovers that his friend, Hiyori, is hiding a huge secret of her own.
Hiyori has to leave Haru and Ena, but Haru wants to reunite with her. Haru misses Hiyori, and so embarks upon a journey across the galaxy to see her: a journey he accomplishes with his wannabe alien-bride Ena and Ena’s trusty maid sidekick Revi.
Though Haru has always loved stargazing, he’s never travelled amongst them before. What will happen during his adventure, and will he be able to rescue Hiyori?
He’s going to do his very best – but things would be a lot easier if Revi would stop flirting with him!

Ena is an alien princess who comes from a planet called Corval. She might be royalty, but she doesn’t act elegant or stuck-up. She’s a cheerful, energetic girl who has a huge passion for Japanese media: especially romance manga.
Ena is outgoing and she isn’t afraid to express her feelings. She fell for Haru from day one, and she’s determined to make him her husband using whatever means necessary.

Hiyori is a gentle girl who’s one year Haru’s senior. She runs the astronomy club at the university she and Haru attend, though until Haru arrived she was its only member. Obsessed with the stars, Hiyori always believed that she was an alien herself: something Haru used to scoff at, until…
Well. Now Haru’s starting to think there might have been some truth to Hiyori’s claims after all.

Revi is Ena’s maid, but she isn’t at all demure. While most maids are meant to be sophisticated, Revi is a cheerful tomboy whose hobbies include preparing the strangest desserts known to mankind and tinkering with spaceships.
Revi owns a spaceship of her own, and she’s an accomplished mechanic and pilot. Revi takes Ena and Haru into space they can reunite with Hiyori, but she’s more interested in teasing Haru than she is acting as a guide during Haru’s interplanetary tour.