Off-duty Japan protection Forces (JSDF) officer and otaku, Youji Itami, is on his thanks to attend a doujin convention in Ginza, Tokio once a mysterious portal within the form of an oversized gate suddenly seems. From this gate, supernatural creatures and warriors clad in medieval armor emerge, charging through town, killing and destroying everything in their path. With swift actions, Youji saves as several lives as he will whereas the remainder of the JSDF direct their efforts towards stopping the invasion. Three months when the attack, Youji has been tasked with leading a special recon team, as a part of a JSDF task force, that may be sent to the planet on the far side the gate—now being named because the "Special Region." they need to travel into this unknown world so as to be told a lot of regarding what they're coping with and arrange to attach the locals in hopes of making peaceful ties with the ruling empire. however if they fail, they face the consequence of collaborating in a very devastating war that may engulf either side of the gate.