Jeon Dojun's new roommate turns out to be Song Jaehee—his former boyfriend, whom he ghosted during high school. Yet Jaehee insists the past is settled, promising Dojun that their university life will remain undisturbed. Though Jaehee appears completely innocent, he is secretly scheming to win Dojun back. After Dojun causes an accident that breaks Jaehee's arm, Jaehee demands an apology in the form of a one-month fake dating arrangement until his arm heals. Dojun is far from enthusiastic, but Jaehee seizes the chance to seduce him, uncover what happened in the past, and potentially transform the four weeks of pretend romance into a lifetime of genuine love.