The decisive battle!!! And beyond that! The greatest fight of Mile and her friends, the "Red Oath," begins! A hugely popular fantasy that has surpassed 450 million PV! Mile, who was reborn in another world, aimed to be an ordinary, plain girl. Yet, she ends up becoming a hunter, helping princesses, resolving wars between nations, and fighting ancient dragons!? And now, the four girls of the "Red Oath" are heading into battle against the invaders with just the four of them! However, to their side come "Wonders Three," fellow hunters, and many people and friends rushing to their aid! The battle to protect Mile and her friends' world begins!