"Gate: Jieitai Kanochi nite, Kaku Tatakaeri" is a manga series that blends fantasy, military, and political intrigue. The story begins when a mysterious gate suddenly appears in the heart of Tokyo’s Ginza district, unleashing an army of medieval-style soldiers and mythical creatures from another world. The invaders cause widespread destruction and chaos before being repelled by the modern Japanese Self-Defense Force (JSDF). Following this event, the JSDF launches a counter-invasion through the gate to investigate the other world, known as the "Special Region," and to establish diplomatic and military control.

The protagonist, Youji Itami, is a JSDF officer and otaku who is unexpectedly thrust into a leadership role during the initial attack in Ginza. As part of the JSDF expeditionary force, Itami leads a reconnaissance mission into the Special Region, where they encounter a diverse array of factions, including humans, elves, and demi-humans, as well as powerful dragons and ancient magic. The Special Region is a politically fragmented land ruled by an empire that seeks to expand its dominion, often through brutal conquest. The JSDF’s advanced technology and tactics give them a significant advantage, but they must navigate complex alliances, cultural misunderstandings, and the ethical implications of their presence in this new world.

Key characters include Rory Mercury, a high-ranking apostle of the god Emroy, who is both a lethal warrior and a mysterious figure with a deep connection to the Special Region’s divine forces. Tuka Luna Marceau, an elf who suffers from trauma after witnessing the death of her family, becomes emotionally dependent on Itami. Lelei La Lalena, a young and intelligent mage, serves as a bridge between the JSDF and the local population, providing insights into the region’s culture and magic. Princess Pina Co Lada, a noble of the empire, seeks to forge a peaceful relationship with the JSDF to prevent further bloodshed and protect her people.

The narrative explores themes of cultural exchange, the clash between modern and medieval societies, and the moral complexities of military intervention. The JSDF’s actions in the Special Region are driven by both strategic interests and humanitarian concerns, but their presence inevitably disrupts the balance of power and sparks resistance from various factions. The story balances intense military action with moments of diplomacy, humor, and character development, creating a multifaceted portrayal of the interactions between two vastly different worlds.