During her summer vacation at her grandfather's house, Hotaru Takegawa, who is only six, becomes lost in a forest that is rumored to be filled with spirits. She wails for help, and then Gin, an enigmatic boy who is wearing a disguise, arrives and offers to assist her. Hotaru is ecstatic to see another person and runs towards Gin with open arms, but he harshly pushes her away. However, she quickly grasps why he acted that way: a terrible curse has been placed on Gin, and if a human touches him, he will vanish forever. Meanwhile, Gin pleas with her to never come back, but instead of accepting his request, Hotaru does the opposite. Eventually, they develop a close friendship despite Gin's fragile situation as the years go by and their mutual feelings intensify. Nonetheless, they start grappling with the limitations that destiny has created and imposed on them.