This is the first fanart I've seen of Yoon. The manhwa is called Plaything, and is about a businessman getting revenge on a group of psychotic school bullies who drove his daughter to suicide, using an even more psychotic girl aptly named Karma as his weapon of choice. Also, she was experimented on as a child by North Korean scientists making her a super-strong monster who doesn't feel pain or empathy. It's worth a read if you don't mind something a little more intense.

Haven't read too much of the series, but definitely some memorable scenes. Certainly remember her face when she death griped one delinquent by the groin and while making sure his friend was watching she crushed it and had a pretty ecstatic grin while the guy's friend just watched in horror while listening to the screaming. Though if I recall they attacked her first... but she commonly sets it up so her actions are "self defense."