Five hundred years ago, the fantasy world of Alneath was torn apart by a war between magically gifted immortals and mortals armed with magical artifacts. The conflict came to an end when mortals' hero, Gram, slayed the Demon Lord Veltol Velvet Velsvolt. In 2099, the world looks a bit different. Alneath and technologically advanced Earth have fused in an event known as Fantasion. Immortals have been hunted down to near extinction, and technological implants called Familia allow mortals to use magic.

As the new world slowly recovers, Veltol's vassal Machina Solege resurrects him in Shinjuku, a techno-magical city constructed in the middle of devastated lands. However, Veltol's magic is severely weakened, and his former ally Marcus has betrayed him. To regain his fame and magical abilities, Veltol follows the advice of Takahashi—Machina's friend and a professional hacker—to start an unusual career: live streaming. His sharp tongue and comically poor gaming skills quickly secure him followers, but to dominate the world once again, Veltol must first uncover Shinjuku's secrets and thwart Marcus' vile plans.