In the centre of Ginza, in Tokyo, a giant door appears. By breaking up hordes of soldiers, monsters and dragons from another age whose invasion is stopped by the Japanese Self-Defense Forces. The counter-attack is not delayed: a small contingent of Japanese troops is sent across the door to discover a country of magic, elfs and trolls. Yôji Itami, soldier and proud otaku, is part of this expedition on the way to discover this new world and to brave its many dangers!