The World After The End

This is about a man who didn't regress when everyone else returned back to the past.Humans were suddenly summoned to become "Walkers", and they needed to clear the tower to save the world. . . Floor 77: The "Stone of Regression" was discovered.Walkers could now "return" to the past. Slowly, everyone left. . . Humanity's last hope, "Carpe Diem", was formed, made up of people who refused to abandon the world. . . The last Walker reached floor 100.He no longer knew what to believe.