Molka by Monika Kim

Dahye has met the man of her dreams - Hyukjoon, who happens to be the heir to a multi-billion fortune. Till one day, a video of them having sex goes viral. She is all over the internet and he is nowhere to be found. Junyoung is a nobody; a nothing office worker who harbours a dark secret: in every women's cubicle, shower and bathroom in his workplace, are cameras - his secret cameras. Junyoung spends his days watching and preying on his unsuspecting female victims. Soon his perverse obsession turns to Dahye - but, this time, he has chosen the wrong woman to wrong. When Dahye's pain turns to blind rage - she decides that she will not rest until he has paid in blood.