When an alien princess unexpectedly lands in Rito Yuuki's bathtub and he becomes entangled in a chaotic intergalactic love affair, his life spirals into a whirlwind of mishaps and misadventures. Despite Princess Lala's growing affections, their relationship is plagued by relentless challenges like bounty hunters, malfunctioning technology, body swaps, and disastrous sleepovers. As they navigate through the mayhem, including the dreaded Valentine's Day, Rito learns the hard way why marrying an extraterrestrial being is a recipe for disaster.