Kuga, who became a dungeon explorer alongside his close friends, ends up being banished from his party due to him being a supposed "jack of all trades, master of none" hero. Amidst his despair, Kuga finds himself thrown into the hidden boss room, famous for making explorers unable to step foot into a dungeon ever again. There, he encounters a beautiful female vampire named Alicia. Though he’s prepared to meet his end, Alicia, captivated by the so-called streaming, has other plans and asks him, "Could you teach me how to stream?" With nowhere else to go, Kuga reluctantly accepts her proposal and thus begins their unprecedented dungeon explorer-hunting streams. For some reason, their stream quickly went viral like crazy, and Kuga then began to awaken some unknown powers...? And meanwhile, something strange is happening to the party members who banished Kuga...