Apocalypse: I was bestowed with an SSS Mjolnir Artifact

Ethan's life has been thrown into chaos by a great catastrophe that has befallen the planet, with a giant dome encasing most people in a city and cutting them off from the rest of the world.
He is one of the "chosen ones" who have been bestowed with power by a System, and tasked with taking on monsters and completing life-threatening challenges.

This is a far cry from the mundane, uneventful life he used to lead.
As he struggles to overcome these dangerous conditions, he can't help but think: "I miss my boring life!"

Can he succeed in his mission? Who is Humanity's true enemy? And who is the mysterious force controlling the System?