INAI BOKU WA HOTARUMACHI NI IRU

Despondent over the death of his best friend, Takeru wishes on a shooting star to meet Takuya one last time. A glimmer of light leads him to an ancient tree stump with a giant hole in it; a hole that impossibly leads to an entire city. It’s the same city as his - the same people and places - but, with a key difference: the Takuya in that world is alive and well... while Takeru is not. — Description from AniList community (anilist.co).