"...W-what should I do? I'm being transported to the battlefield of hell!"

In the midst of the war against the demonic beasts, where humanity faces the threat of extinction, the maid girl Orsela accidentally finds herself transferred to a forest on the front lines of the battlefield. She has no weapons or combat experience; all she possesses is her seemingly useless inherent magic, which can only summon things that people no longer need. When she encounters a large magical beast—a dragon—and finds herself in a desperate, life-threatening situation, she gambles everything and summons a magical weapon: a revolver, and a battle-crazed girl of heroic class!?

The magic that was thought to be useless turns out to be more suited for battle than any other magic... Before she knows it, she becomes the last bastion protecting humanity! The weakest class maid carves out a future for mankind!