Kim Jae Hwan is the voice behind "What If" for the 'Record of Youth' OST. 

The music video above follows Ahn Jung Ha (played by Park So Dam) and Sa Hye Jun (Park Bo Gum) as they comfort each other during their stressful day-to-day and become more than friends. "What If" is about not knowing how much you needed someone in your life and wondering if it's love you're feeling. 

Listen to Kim Jae Hwan's "What If" above! Have you been watching 'Record of Youth'?