After being left by her boyfriend just shy of their 100-day milestone, Ha-Young encounters a college student named Hyung-Joon when she inadvertently kicks a can that strikes him in the face, leading to a scratch on his Lexus. He insists she pay him $3000 immediately. She manages to flee, but leaves her wallet behind. Hyung-Joon tracks her down, demanding compensation for his car. As a financially strapped high schooler, Ha-Young is forced to sign an “Enslavement Agreement” to cover the repair costs. This agreement plunges her into a grueling 100-day ordeal, where she must clean his house, run his errands, do his homework, and wash his car. Eventually, she discovers that the actual repair cost is only $10, prompting her to seek revenge. However, Hyung-Joon unexpectedly reappears at her home as her new tutor. He continues to exploit her, but soon Ha-Young finds herself unexpectedly falling for him.