Mask (2015)

Byeon Ji Suk, burdened by her father’s debts and relentless loan sharks, dreams of a better life. A twist of fate introduces her to Eun Ha, a wealthy woman who looks just like her. Seizing the chance, Ji Suk assumes Eun Ha’s identity and steps into an elite world, where she meets Min U, a wary chaebol heir drawn to her authenticity. But how long can Ji Suk maintain the façade and conceal her true self? (Source: MyDramaList)