Arata naru Sekai: Kako-hen

We came from the far future, where most of the adults have disappeared as if they vanished into thin air and all of the children are managed by a few adults. To discover the cause behind human extinction and to evade it from that root cause... That's what we had jumped to the past for, supposedly. A boy sitting in the seats of a movie theater fidgets with his cellphone. "Before aptitude or anything, trying to change the future with just five kids? You would think there's a limit to lack of plan...