Hotarubi no Mori e
蛍火の杜へ (original)
One hot summer day a little girl gets lost in an enchanted forest of the mountain god where spirits reside. A young boy appears before her, but she cannot touch him for fear of making him disappear. And so a wondrous adventure awaits...
Starring Izumi Sawada, Hayato Taya, Ayane Sakura, Koki Uchiyama, Shinpachi Tsuji, Kanehira Yamamoto, Masanori Machida, Mami Uchida, Hiroki Goto, Kumiko Tashiro
It's a romance and animation movie, and has a rating of 7.8 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from United States.