After years of obscurity, rising star Sung Yi-hyun is finally basking in the spotlight... Conquering dramas, variety shows, and the glitz of celebrity life. Then one day, he gets a single text from his longtime lover, Jang Tae-eun: “Let’s break up.” Ghosted. Dumped. By text. One of the three ultimate breakup sins. Furious, Yi-hyun swears to live his best, wildest life—eating well, partying hard, and pretending not to care. But Tae-eun doesn’t even flinch. “Don’t tell me… he’s seeing someone else?” When Yi-hyun storms over to confront him, he's greeted not by his ex—but by the biggest, brightest full moon he’s ever seen. And just like that, the secret he’s kept hidden for years is exposed… along with a tail and a pair of ears. Mistaken for a stray and taken in by Tae-eun, Yi-hyun suddenly finds himself living under the same roof as his ex— not as a man, but as a dog named Rufus. A sweet ex, a secret shifter, and one very suspiciously adorable dog— let the dangerously cute cohabitation begin!