Dara-San Of Reiwa (Manga) Vol 01

Clouds blacken the sky and sheets of rain turn the mountain forest into a treacherous maze... A landslide crushes a razor wire fence, and buries a "NO TRESPASSING" sign... Two young siblings wander into a dark world where they do not belong, and a long, horrid shadow rears up to meet them-Anyway, so that's how we met Dara-san! She might look kinda scary, but just wait until you get to know her! Yen Press
(W) Haruomi Tomotsuka