Working after school isn't making enough money for her eomma's hospital bills. Han Rika decides to seek out her father, President Han of Pledis Ent., after years of not seeing him every since he abandoned Rika and her eomma. She's thrown to be the company slave, doing odd jobs and being bossed around by everyone. Even worse is her father's new wife and her daughter Hyorin, who find any chance to abuse Rika. Because of her beautiful voice, they even force her sing to for Hyorin to lip synch to, because Hyorin is an idol at Pledis Ent. but can't sing at all. The boys of Seventeen know that the voice isn't Hyorin's, and a few of them fall in love with Rika's voice, desperate to find the mystery girl who's being made to sing for the President's brat daughter. Little do they know, the girl who runs their errands- the silent but pretty girl who's being treated less than human at their company, is the girl with the beautiful voice. The boys of Seventeen look out for Rika as much as they can, but what will happen when they start to realise that she's the mystery singer? What happens when more than one of them are in love with Rika in more than one way? What happens when Rika starts to be noticed for her talents by other labels like Bighit Ent. , and befriends the crazy boys of Bangtan Boys? Follow Rika in her story, as a Diamond in the Rough.