Zero, a young nobleman reborn in a sword-and-magic fantasy world after dying in modern Japan, feels his former otaku instincts surge. Craving some chuunibyou-style fun, he stumbles upon his father's old notebook, the "Notebook of the World's Truths," a piece of embarrassing family history filled with grandiose conspiracy lore. Seizing the opportunity, Zero adopts the persona of the Emissary of the Holy God, the one true deity, and declares war on the false gods that supposedly rule the world. He recruits a few local girls on a whim, spinning elaborate stories about a secret shadow organization fighting the corrupt divine order. To his shock, the gods are real, and his roleplay becomes reality. The girls he casually enlisted now worship him with fanatical devotion, and his made-up organization begins to take on a life of its own. Trapped by his own lies and unable to back down, Zero must continue playing the part of the divine proxy, leading a genuine secret society and manipulating events from the shadows, all while desperately wishing he could quit. His absurd, unintended influence reshapes the world around him, turning a joke into a real and hilarious power struggle.