A hardcore gamer known online as Zephyrus has dedicated over 8000 hours to the legendary dungeon-crawling RPG Dungeon Shukatsu no Susume, commonly shortened to Dan-Katsu. After losing his entire save data, the shock causes his death, but he awakens to find himself reincarnated inside the game world he thought he knew perfectly. He stands in the Village of the Beginning without a Name, the very location from the screen, and realizes he has been given the chance to play the real thing.

The protagonist Zephyrus is a veteran player whose obsessive knowledge of game mechanics becomes his greatest asset. Unlike a typical new player, he immediately secures the Hero class, widely considered the strongest job in the game. However, he quickly discovers that the world of Dan-Katsu is far from conquered. The most difficult dungeons remain unexplored, and the local players perceive certain classes very differently than he expected. For instance, the Muscle Warrior class, which he considered a joke or for-fun build in the original game, is actually respected in this reality. Far from being discouraged, Zephyrus is overjoyed. He treats his situation as a New Game Plus, ready to fully enjoy the immersive fantasy experience he always dreamed of.

The main setting for the narrative is Labyrinth Academy, the central location where the game’s main story unfolds. From this hub, Zephyrus begins assembling a diverse party of companions. He actively uses his meta-knowledge to optimize those around him, guiding his reserved childhood friend to become a powerful Alchemist and transforming a selfish princess into a Saint. By gathering these unique and powerful classes, he prepares to challenge dungeons that have never been conquered before.

The narrative arc follows Zephyrus as he uses his player knowledge to break the game world’s balance. While his primary goal is to have fun exploring every corner of this new reality, the story focuses on his journey from a shocked player to a legendary hero. He brings together his classmates, demonstrates what truly makes a class good, and aims to complete a game that has over 1021 classes and more than 400 possible endings, now with his real life on the line.