Gate

Gate begins when a mysterious portal opens in Tokyo's Ginza district and unleashes monsters, medieval knights, and other fantasy beings into the city. The deadly attack becomes known as the Ginza Incident. In response, the Japanese Self-Defense Forces send a small unit through the gate to investigate the alternate world beyond it. Led by soldier Youji Itami, the group encounters villages threatened by a dragon and meets an elf girl who survived one of its attacks. Their mission becomes an expedition through a dangerous world where modern soldiers and fantasy civilizations suddenly occupy the same conflict.