It's been three years since dungeons were created. In a world where conquering dungeons has become normal, the corporate slave Yoshimura has an unexpected misfortune. By coincidence, he now ranks #1 in the world!

Longing for a leisurely life, he decides to retire and dive into dungeons, but is swept away by the unknown skill he has acquired and becomes involved in the front line of dungeon exploits. Where will this slow life lead him to tomorrow?