Read manga I Pick Up Trash in the Apocalypse
The male antagonist is a Demon Sovereign with the power to destroy the heavens and the earth. If he conquers the final city, the entire continent will fall under his control. The heroine of this final city is just as formidable, having also reached the brink of godhood.
On this fateful day, their battle shook the heavens and the earth. But suddenly, countless thunderbolts descended from the sky. In an instant, the entire continent—and even the entire planet—was reduced to a post-apocalyptic wasteland.
When the male lead awakens, he discovers that his cultivation has been halved, dropping him to the Foundation Establishment stage. Left with no choice, he embarks on a journey of scavenging in the ruins, slowly rebuilding his strength step by step.