Lufas Maphaahl, the black-winged overlord and leader of the Twelves Stars of Heaven, has been vanquished. A man wakes up in the body of the Exgate game character Lufas, two hundred years after her defeat at the hands of the seven heroes. The game world of Exgate he knew is no longer ruled by humans—and it is no longer just a game. Exgate is a world of its own where the characters think, feel, and live just like he does. Lufas journeys through Exgate, looking for the long-disbanded Twelve Stars of Heaven. Lufas is without country, army, or allies. A question remains: what is the real reason an ordinary man was reincarnated into Exgate as Lufas?

Atsuko "Akko-chan" Kagami (known variously as "Stilly," "Caroline," or "Julie" in Western versions of the anime) is an energetic elementary school girl who has an affinity for mirrors. One day, her favorite mirror which was given to Akko by her mother (or in some versions, by her father, as a present from India) is broken, and she prefers to bury it in her yard rather than throw it to the trash can. In her dreams, she is contacted by a spirit (or in some cases the Queen of the Mirror Kingdom) who is moved that the little girl would treat the mirror so respectfully and not simply throw it away. Akko-chan is then given the gift of a magical mirror and taught an enchantment that will allow her to transform into anything she wishes.

Melphiera Marchalrayd, the daughter of a count, dedicates her time to researching the culinary possibilities of monster meat—a peculiar endeavor started by her late mother. By teaching the people of the Marchalrayd lands to prepare such exotic ingredients, Melphiera hopes to help stave off famine. Unfortunately, her unique tastes and intimate knowledge of monsters have led to her social isolation: few nobles interact with her willingly, disdainfully calling her the "Voracious Villainess." When a monster attack erupts at a royal banquet—where Melphiera has been sent to find a husband—Aristide Rogier du Galbraith, the younger brother of the crown prince, leaps to her aid. Due to his terrifying skill in slaying monsters, Aristide has earned the title of "Blood-Man Duke." Charmed by Melphiera's fearlessness and intriguing culinary prowess, Aristide soon declares his intent to propose. Together, Melphiera and Aristide, high society's most eccentric couple, strive to see beyond the cruel rumors and encourage each other's fascination with monsters and the art of preparing them.

When Light is kicked out of the Concord of the Tribes, his former comrades instantly turn on him. Light escapes this diabolical act of betrayal by the skin of his teeth...only to find himself in the deepest part of the Abyss, the most dangerous dungeon in the realm! To avoid being eaten by carnivorous monsters, he uses the Unlimited Gacha, his sole magical skill. But where it previously only produced junk items, this time Mei—a gorgeous Level 9999 fighter in a maid outfit—springs forth! Fast forward three years and Light has carved out his own kingdom in this backwater dungeon, summoning more beautiful Level 9999 warriors who swear absolute fealty to him. Now a powerful Level 9999 Overlord himself, Light plans to ascend to the surface and take revenge on his betrayers one by one!