My world was already destroyed five minutes ago, but I'm living without a care in the world anyway.

This novel is a story of world destruction and recreation. An ordinary high school student encountered world collapse on their way to school, and due to a childhood friend who couldn't stop the villain, it became a world destruction. This is probably the story. Do you think it's boring? But you see, if you encountered world collapse on your way to school, what would you do?