In August of 20XX, a portal to a parallel world, known as the “Gate,” suddenly appeared in Ginza, Tokyo. Monsters and troops poured out of the portal, turning the shopping district into a bloody inferno. The Japan Ground-Self Defence Force immediately took action and pushed the fantasy creatures back to the “Gate.” To facilitate negotiations and prepare for future fights, the JGSDF dispatched the Third Reconnaissance Team to the “Special Region” at the other side of the Gate. Youji Itami, a JSDF officer as well as a 33-year-old otaku, was appointed as the leader of the Team. Amid attacks from enemy troops the team visited a variety of places and learnt a lot about the local culture and geography.
Yoji Itami get promoted to First Lieutenant after the Ginza Incident, and lead an investigation team to explore the “Special Region”. While they’re investigating a village which been destroyed by Fire Dragon, three young local ladies; a sorcerer, an elf and a demi-goddess, join their team.The victims of Ginza Incident demand Japanese government to claim compensation from the Imperial, however the negotiation is not going well as the Imperial lack of knowledge of human rights and international law. Meanwhile, world nations, which covet the profit from Special Region, start to intervene Self-Defense Force’s action at another side of “Gate”. In another hand, the SDF approaches and communicate with the villagers, thus Japaneses culture gradually spread over the Special Region…