I Stole the First Ranker's Soul

Moa Son, an ordinary office worker, wakes up in a dungeon in the middle of the night and awakens as a collecting hunter. After barely making it out alive, she falls into the same dungeon but gets rescued by the first-ranked hunter, Jihan Seo, and becomes bound up with him. Now he's offering to make her strong on this one condition—"Promise me you will do your best to kill the bosses of all the dungeons that exist in the world." Come again?

(Source: Webtoon Entertainment)