The Cleaner with a Billion-Dollar Secret

The female lead, secretly the heiress to San Francisco's wealthiest family, works as a janitor and anonymously invests $100 million to save her boyfriend (second male lead)'s failing company. While delivering him lunch, she's mistaken by the male lead—heir to New York's richest dynasty—as a contractual marriage candidate. After being publicly humiliated when her boyfriend cheats on her, she accepts the male lead's marriage proposal. Their union faces relentless mockery from her ex and his new partner, while the male lead's family pressures him to marry the "real" San Francisco heiress (unbeknownst to them, the female lead herself). Enduring scorn while hiding her identity, she's moved by the male lead's unconditional love. Ultimately, she reveals her true status, silencing all critics, and secures her happily-ever-after with the male lead.