THE RELATIVE WORLDS

The film centers on Shin and Kotori, who are both third years in high school. Shin lost his mother when he was little, and since then he has a tendency to close himself off. Kotori is his childhood friend who always looks out for him. One day, another "self" from another Japan appears in front of them. (Source: Anime News Network) — Description from AniList community (anilist.co).