Kim Sere - a pressured, high school girl who has spent her whole life living for her mother's pride, forced to be the top student in her class. While Ahn Keonho is the complete opposite - he is carefree, a swimming athlete, a model, can sing and dance, and raised only by his older sister. No pressure. No expectations. Just freedom. He is almost perfect. What happens when a blue sea leads them together?

Moving in with her best friend was supposed to be the perfect plan-late-night talks, shared snacks, and someone who actually understands her. But when she drags her luggage across the apartment, she doesn't find her best friend waiting... she finds him. Her best friend's older brother. Her worst enemy since high school. And... her new roommate. He's loud, annoying, and spends every night yelling into his headset while playing Call of Duty. She's smart, quiet, organized, and already counting the days until she can escape and move out. But the longer they're stuck together, the more the lines between hate and something else start to blur. Who knows? the wrong roommate might just turn out to be the right one.