Gate

Gate begins with a sudden catastrophe in Ginza, Tokyo, when a mysterious portal shaped like a massive gate opens and releases monsters and warriors in medieval armor into the city, killing civilians and wrecking everything in their path. Off-duty Japan Self-Defense Forces officer and otaku Youji Itami is caught in the chaos while trying to rescue as many people as he can, and the JSDF responds with overwhelming force to contain the attack. After the crisis, Itami is placed in command of a special reconnaissance team within a JSDF task force sent beyond the gate to the world known as the Special Region. Beyond the portal, the soldiers must chart unknown territory, identify who and what lies behind the invasion, and determine whether the two worlds can coexist before political friction turns into a larger war. As Itami and his team negotiate with local rulers, face hostile forces, and work under constant military pressure, Gate follows the larger conflict between modern Japan and the empire on the other side of the doorway, blending diplomacy, exploration, and armed confrontation.