Me + UFO = Collapsing World

A boy named Kizu Yoya was once abducted by a UFO. That said, he didn't particularly worry about it and lived a carefree life. However, as if to mock such Yoya, they once again reach out their evil hands toward him!! And the next place he awoke was in the middle of a vast wasteland that stretched across the entire horizon. There he encounters people who survive and thrive in a collapsed world, and he himself is forced to live alongside them.