Yeonui Pyeonji Episode 1

Sori is a unique young girl: kind, caring and principled well beyond her years. Unfortunately, these qualities also make her a prime target for bullying. She transfers schools, and just when it looks like history is about to repeat itself, stumbles across a mysterious trail of letters that takes her on a magical scavenger hunt through a hidden world that exists just beneath the surface of her new middle school... A scavenger hunt that will lead her to rediscover friendship, the wonders of nature, and the goodness that still exists within humanity.

(Source: WEBTOONS)