An entryway shows up in Tokyo's Ginza area at some point in the 21st century. From the door spills out creatures, knights from middle-age Europe, and other dream like creatures, and they slaughter a number of the subjects of Tokyo. This occasion is known as the Ginza Incident. The administration sends a little gathering of officers from the Japanese Self-Defense Forces to the substitute world past the door. Driven by otaku officer Yoji, they find that the towns on the planet are being assaulted by a mythical serpent. A mythical person young lady who is a survivor from the monster's frenzy joins the gathering in their goes over the unsafe new world.