Shi ni Modoru Maou-kyuu Player Lostman

Dungeons have emerged in the modern era, where players with skill compete within them. Kanzaki Yukari aspires to conquer the challenging Luluheart Dungeon but is considered "Skillless," preventing him from entering. When a "Dungeon Break" causes monsters to spill out, he rescues a severely wounded girl. She is revealed to be the Demon Lord Luluheart, who offers him a chance to save the world by traveling back in time. Yukari returns to a point six years earlier and uses his "Return by Death" ability to fight in a battle that will determine the world's fate.