In Oh! My Assistant, Seon Ho is a writer who, two years ago, was short on money, so decided to try to improve his financial situation by creating racy web-based cartoon strips (also known as webtoons). Known as “19+” titles, these webtoons may only be read by those aged 19 or above. Seon Ho’s titles have become extremely popular. But they have had a very unexpected effect on his sex drive. Since he began writing, he cannot feel aroused. He has also become extremely busy, as his titles are in great demand. So Seon Ho decides to hire an assistant to help him meet his deadlines. The assistant, Mu Young, turns out to be a reader – Seon Ho’s number one fan, in fact. As they start to work together, they start to feel the pull of mutual attraction. But one of Mu Young’s male acquaintances, a young man called Jun Seok starts to fall for Mu Young – even though he has a girlfriend. Will Seon Ho’s sex drive ever return? And could he find love with Mu Young?