The story depicts a sudden "gate to another world" in Ginza, Tokyo in 20XX, from which a large number of monsters and troops emerged. While the Ground Self-Defense Force repelled them, they also rushed to the "special zone" on the other side of the gate. As a result, Yoshi Itami, a second-class land guard who served as the commander of the third reconnaissance team, had a wonderful exchange with beautiful girls from other worlds such as elves, magicians and gods while helping the villagers attacked by a giant fire dragon.