Hotarubi no Mori e
The original manga and movie have the same story. A six-year-old girl called Hotaru Takegawa gets lost in a forest. Many yamagami and yōkai live in this forest. A person wearing a mask called Gin finds Hotaru. Gin tells Hotaru that if she touches him, he will disappear. He helps Hotaru get out of the forest. Later, Hotaru keeps visiting Gin in the forest. They become friends, but Hotaru has to go back home in the city for school. Hotaru promises Gin that she will keep coming back each year.