Gate: Jieitai Kanochi nite, Kaku Tatakaeri S01

Everything starts with the opening of a gate; chaos in the Ginza district of Tokyo reaches its peak when a gate opens to a time period in the 21st century, and the opening of this gate is equivalent to a massive influx of monsters into Tokyo and the attack of these creatures on the innocent people of the city, creating a great terror that has never been seen on earth. But it's not just monsters that have invaded the city and this region; medieval knights and other fantasy creatures also find their way from this gate into the city of Tokyo, and the world that has been living in peace until now is now immersed in an unbelievable turmoil. This event is later named the "Ginza Incident." The Japanese government does not remain idle in the face of this event, taking action to prevent the occurrence of even greater disasters as soon as possible, sending a group of the country's defensive and security soldiers through the created gate into another world. Following their entry into the fantasy world of the story, the group of soldiers, led by an otaku named "Yoji Itami," encounters villagers who are being attacked by a dragon; after this encounter, an elf girl also joins the group of soldiers and sets foot on an adventure in this new and wondrous world.