Gate (location), Gate - Thus the JSDF Fought There! Wiki

The Gate is a mysterious Dimensional Portal which appeared in the Ginza district of Tokyo in 20xx, which connected Japan to Alnus Hill, Special Region. As soon as it appeared, the Imperial Army invaded through the Gate and began to indiscriminately kill or capture every civilians by terrorism they encountered, and overwhelming attempts by police forces to halt their advance failed. It was at that time that Yōji Itami took command of the Tokyo police in the area and led an evacuation of civilians

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