Shi ni Modoru Maou-kyuu Player Lostman

Dungeons have appeared in the modern world, where skilled players compete against each other. There, there is a young man named Kanzaki Yukari who dreams of conquering the most difficult "Luluheart Dungeon." However, he is incompetent and has been branded "Skillless," meaning he cannot even enter the dungeon. One day, a "Dungeon Break" occurs, causing monsters to overflow from the dungeon, and he saves a seriously injured girl. Her true identity is the Demon Lord Luluheart, who gives him a "chance to save the world." That is, to go back in time with Luluheart's power. Yukari, who has returned to six years ago, uses his ability "Return by Death" to take on the battle to save the world!

(Source: Whomor, translated)