Young Boss

At the end of a dull romance, preparing for marriage as an ordinary office worker, Kang Si-hyun. In front of her, the child she once took care of, Yoon Tae-ha, appears. He's the newly appointed chief, in other words, Si-hyun's boss. "You can't do this to me. Even if you're the last man on earth, we can't be together!" The adorable little boy, who used to be so cute, now looks at her with the eyes of a man and says. "Marry me instead."

(Source: Naver, translated)