Ah yes, a Korean series following the Japanese Isekai trope. This series does take place during the era of royals and magic like Katarina. There is one great edge of this series, it lies with the MC" 's purely committed resolve to become good and the sister. The sister who is originally an evil character has....hidden variables not even the MC has accounted for. This makes this series much more interesting and allows room for great twists. You can change a story but there will always be some aspects out of your control. Intervention is the prime example of this. The art might seem somewhat bizarre at times but it'snot an issue with the detailed development.