When Kei Kusanagi stumbles upon a luminous woman near a lake, little does he know she's an extraterrestrial officer named Mizuho Kazami from the Galaxy Federation—and shockingly, his teacher too! Despite the unexpected twist, Kei and Mizuho gradually bond and kindle a romance. However, their love faces a hurdle when the school principal uncovers their relationship. The unconventional solution? Tying the knot! Now, as clandestine newlyweds, they must navigate the complexities of concealing their union from both Kei's peers and the Galaxy Federation. Onegai☆Teacher unfolds the tender yet amusing tale of an alien and her student in a delicate dance of love.