[wellis]

Well someone on Spacebattles was able to translate a portion of the prologue from the sample page:

Originally Posted by Prologue 1, first part
20××, Summer

According to records, the day was humid and hot.
The temperature exceeded 30°C, the level of humidity was high too, and due to the influence of a heat island the streets had turned into a scorching hell.
Nevertheless, it was Saturday. Lots of people went to the city centre and had fun buying things or window shopping.

11:50 am

The sun was approaching the zenith, and when it seemed like the temperature would reach a new record, in Ginza, central ward of the Tokyo metropolitan area, suddenly a "Gate to Another World" appeared.
Knights and infantry that, from the looks of their armor, seemed to be straight from medieval Europe came pouring out. And then... What came then seemed like it belonged into a fantasy story or movie: Fantastical beings like orcs, goblins and trolls.
They charged the people that, by chance, happened to be present.
Young and old, men and women, no matter the race or nationality, slaughtering everyone seemed to be their objective.
The people, having gotten used to this peaceful country in these peaceful times, had no way to resist. In this pandemonium of shrieks, one by one they fell.
The shoppers, the parents with their children, and tourists from overseas, one by one they were trampled down under horse's hooves, pierced by lances and cut down by swords.
Heaps of corpses covered the streets, and the asphalt of Ginza turned the dark red colour of blood. "Hell" would have been a fitting title for the scene.
The troops of the other world stacked even more corpses on top of the piled up ones. Then, on this hill of meat, a jet black battle flag was hoisted. And with their loud voices, in their own language, they declared this place conquered and in their possession.
Although, since there was nobody to listen to them, it was a one-sided proclamation of war.

"The Ginza Incident"

This is what history would later call this touching of the other world with ours.