Kanzaki Reito was one of the lucky few to win a spot as a test player for the next-generation VRMMO, Astral Border. However, upon entering, he was informed by the Guide AI that he would be unable to log out until he cleared the game. Alongside a group of like-minded comrades, Reito reached the theoretical level cap and successfully defeated the final boss, the Demon God. But victory came at a heavy price: his three companions lost their lives in the struggle. Believing that “clearing the game is meaningless without my friends,” Reito used a skill to resurrect them at the cost of his own life—yet, for some reason, he opens his eyes back in reality. “Did I… log out?” The three years he spent inside the VRMMO amounted to only three days in the real world. Awakened by a younger sister he has no memory of, Reito feels a lingering sense of unease, realizing that the reality he knew has changed. On his way back to school for the first time in days, he encounters a terrifying scene: monsters appearing in the middle of the city. Unable to ignore those being attacked, Reito jumps in to help—and realizes something impossible. “I can use my skills… in reality…?” Though the skill Reito used was a basic one, it appeared far from ordinary to those around him. In a world where schools now hold classes on how to handle skills and conduct practical training in dungeons, Reito gradually comes to understand the truth: His abilities, forged through the title of “Demon God Slayer,” are completely off-the-charts even in this new reality.