In modern-day Japan, where dungeons have suddenly appeared worldwide, our protagonist, Rei Omomo, is a true introvert in real life but is the only person in the world with a maxed-out level in the dungeons. Rei, who has cut off ties with society to fully immerse himself in dungeons, ends up saving the famous cute streamer "Yuria," who has 10 million subscribers, from a crisis one day. Unintentionally going viral through dungeon streaming, Rei finds himself dragged deeper into the mysteries of the dungeons—mysteries involving the underworld and even national governments—despite his wish for a peaceful life.