Lee Y/N, a young girl with a very interesting past, ends up in Songrim along with her sister. There she runs into a Young Master named Seo Yul, but it turns out they already know each other. She's the one thing he'd been taught his whole life to kill, but can he kill the girl from his past that he fell in love with? Or despite barriers will they fight for each other? Seo Yul X Reader