Morishita Daiki became a hero after being summoned to another world. After skillfully striking down the Demon Lord, he returned to Japan. Daiki, with his strength concealed, was living a tranquil day-to-day life. However, apparitions and those with special powers run rampant in this seemingly-normal world. A supernatural school-battle epic rarely seen in the modern era unfolds in the shadows!! A story about an unbelievably strong hero returning to the modern era after his adventures in another world!

The story begins when the gods call a conference to decide the whether to let humanity live or die, and settle on destroying humanity. But a lone valkyrie puts forward a suggestion to let the gods and humanity fight one last battle, as a last hope for humanity's continued survival. 13 gods will fight against 13 human champions in one-on-one battles to decide whether humanity lives or dies.