Koyomi doesn't know which world he's actually from, and neither do you until the very end, which means you're grieving a relationship that might not have ever existed in his timeline. The film asks the cruelest question: if she's from a world where you loved each other, and you have no memory of it, does that love count? A young man trying to figure out if he's the imposter in someone else's story, watching someone choose him anyway.
Koyomi has spent years isolated, struggling to connect with anyone after his parents split. Everything changes when he meets Kazune, a girl who seems oddly familiar despite their first encounter feeling brand new. She drops a revelation that shatters his understanding of reality: she's traveled from an alternate dimension where the two of them are already in love. In a world where crossing between parallel universes has become routine, Koyomi faces an unsettling question. If Kazune can jump between worlds, what if he's not from this one at all? What if his entire life, his loneliness, his sense of displacement, stems from belonging somewhere else entirely? The film weaves together the ache of adolescent disconnection with the sci-fi possibility of finding your place across infinite realities. Romance blooms against a backdrop of dimensional travel and fractured identities, asking whether love can exist unchanged across different versions of the world, or if every universe rewrites the story.