Fate Night: On the Eve of Empire

I thought I had transmigrated into a historical scenario set on Earth in the third century AD.

Just as the protagonist was planning to rely on the "Library of the Ages" in his head to crush all opposition and sweep across the land,

a sweet shout suddenly rang out from the east!

"Excalibur: Sword of Promised Victory!!!!"

A pillar of light descended from the heavens, shrouding the entire sky.

The protagonist watched expressionlessly as the pillar of light erased a city from this world.

Then he slowly uttered two words.

"Holy crap..."