Wild Thing

Fantasy?

same as normal universe but with beasts suddenly popping out in various cities' forests

During the Song's family camping vacation, a violent storm make the two siblings Roxy and Märten drift away, lefting them lost in a big forest.
The girl then begins her journey to find her brother, while dealing with the infamous wild beasts that haunt the woods (and maybe find out the misteries behind them).

Based on curses. Like various entity or divinity can curse humans, more likely teenagers, for their wrong actions or for punishing them. One example is Circe's curse, that affects the majority of the beasts: whoever feel their humanity is slowly going away, or their instinct replacing their morals- who's becoming a wild, feral beast- is going through Circe's curse.