I'm Not a Plumber, I'm the Hidden Heir.

Leon dropped out and took work unblocking drains because his father is dying and the treatment has to be paid for. What he does not know is that his parents are both fine and the illness is staged, a test set up by a family that owns one of the largest fortunes in the country and needs to know what their only heir is made of. On a repair job he meets Sophie, the coldest and most admired girl on her campus, who has just been thrown out by her own family for refusing the marriage they arranged with the Zheng family. Leon lets her stay at his place. Living in the same rooms wears down the distance between them and they agree to pose as a couple, which solves a problem for each of them. Zheng Tianhao, who wanted Sophie and did not get her, takes it out on Leon by having him fired, then starts going after Sophie's father's business. Around then Leon is appointed general manager of the Falk Group and put in charge of the bidding on a major contract, and the people who have been humiliating him find out who has been signing the paperwork.