Entranced by the folklore of a mountain deity, six-year-old Hotaru Takegawa wanders off course in the ancient woods during a visit to her uncle. Lost and weary, she stumbles upon a veiled forest spirit named Gin, who cautions her against physical contact to prevent his vanishing. Against this warning, Gin guides Hotaru to safety and instructs her to refrain from returning, a request she disregards as she promises future visits. Despite the barriers of distance and existence, Hotaru and Gin develop a deep bond over consecutive summer encounters. Their profound friendship is tested when affection transcends companionship, challenging the delicate balance of their relationship. Adapted from Yuki Midorikawa's manga, 'Hotarubi no Mori e' narrates the poignant tale of intertwined fates and the intricate dance of friendship and sacrifice between two souls destined to never intertwine.