Akdanggwa Akdangi Mannamyeon

Atalante is the boss of a notorious organization that works in the empire’s shadow. One day, she receives a request from the emperor to assassinate a new target: the tyrant archduke Lionel Vianc. Reluctantly leaving behind her simple life with her members, Atalante heads off to perform the assassination, but for some reason… the archduke doesn’t die. After a mixup between a love potion and poison, Atalante finds herself in a frustrating predicament as the tyrant archduke not only refuses to die… but has also fallen in love with her!

(Source: WEBTOONS)