Awaking to absolute chaos and carnage while on a school trip, Yogiri Takatou discovers that everyone in his class has been transported to another world! He had somehow managed to sleep through the entire ordeal himself, missing out on the Gift — powers bestowed upon the others by a mysterious Sage who appeared to transport them. Even worse, he and another classmate were ruthlessly abandoned by their friends, left as bait to distract a nearby dragon. Although not terribly bothered by the thought of dying, he reluctantly decides to protect his lone companion. After all, a lowly Level 1000 monster doesn't stand a chance against his secret power to invoke Instant Death with a single thought! If he can stay awake long enough to bother using it, that is...

After his high school graduation, Yuuki Wakura realizes it has been five years since his sister's disappearance during a "Mato disaster." Throughout Japan, mysterious entrances have opened to a dimension called "Mato"—a demonic metropolis filled with disastrous monsters known as the "Shuuki" that threaten the safety of humans. However, a new hope arose, as the discovery of a Mato fruit that grants supernatural abilities exclusively to women allowed them to fight against the Shuuki. Due to this, a new matriarchal government was formed, establishing a female organization called the Anti-Demon Corps, which caused men to fall to the bottom of society. When Yuuki suddenly finds himself in Mato, he is unable to escape on his own. But just as he anticipates a gruesome end by the Shuuki, a girl in a militia outfit appears and protects him. As the chief of the Seventh Unit of the Anti-Demon Corps, Kyouka Uzen is ambitious yet devalued by her own peers due to her power being deemed unusual. Now in a life-or-death situation, Kyouka takes the opportunity to find out the true potential of her superpower by using Yuuki: in order to defeat the Shuuki, he has to become her slave.

In a world where the Demon King has died, a host of demigods capable of felling him have inherited the world. A master fencer who can figure out how to take out their opponents with a single glance; a lancer so swift they can break the sound barrier; a wyvern rogue who fights with three legendary weapons at once; an all-powerful wizard who can speak thoughts into being; an angelic assassin who deals instant death. Eager to attain the title of "True Hero," these champions each pursue challenges against formidable foes and spark conflicts among themselves. The battle to determine the mightiest of the mighty begins.