Pokgunui Nunaro Sandaneun Geoseun

If there’s one thing that ruins a good story, it’s a cliché! Handsome prince? Lame. Damsel in distress? Yawn. Knight in shining armor? Depends... How good is he in bed? Wait, HUH?! Well, Yuna Han is out to make sure her sister’s story is anything but a cliché, only now she'll have to live inside of it. And luckily, she plays a fairly minor role. Her only crime is being the main villain's older sister! Can she manage to save both her sister's story AND her own neck before we reach the final page?
(Source: Tapas)
Note: Chapter count includes a 8-chapter side story