The Tarnished Traveling Between the Ordinary and Extraordinary

After transmigrating to another world and becoming an immortal Tarnished, he is chosen by the gods as their last believer to transmigrate once more, seeking power from another world so he can become Elden Lord and save his shattered homeland.

A heroic epic brimming with dread begins! ...At least, that was how it was supposed to go.

His companions in the other world turn out to include the Gray Witch? And he becomes Kaguya Shinomiya's half-brother on her father's side? He has to study hard so he doesn't bring shame on the Shinomiya family?

As if he would ever do something like that! This isn't how things are supposed to go! He's a Tarnished! He has to fight for the world!

He runs away from the Shinomiya family and from school... then meets a rock girl. A girl who plays rock music seems pretty interesting, doesn't she?

Ah, no, he has to save the world!

...But he's too weak right now. Maybe he'd better wait a while and get stronger first!

With that thought in mind, one day after another passes, until one day... the idol statue that had been mistaken for a figurine finally loses patience and unceremoniously hurls him into a new world.

Thus begins a tale that moves between the everyday and the extraordinary, and a saga of war and death.

(P.S. The story starts out as everyday life, then becomes an infinite-world adventure. The everyday-life world is the main world, and he can travel back and forth to it.)