In modern Japan, where Dungeons suddenly appeared all over the world. Rei Oomomo is a true In-kya in the real world, but in the Dungeon, he is the only one in the world whose Level has reached the cap. Rei, who had cut off all social contact and devoted himself entirely to Dungeons, one day saves Yulia, a famous beautiful streamer with 10 million Channel subscribers. Having unintentionally gone Buzz-ing through a Dungeon livestream, Rei, contrary to his desire for a peaceful daily life, gets dragged into further secrets of the Dungeons involving the underworld and even the nation!