Fate/Grand Order: Ordeal Call II - Id

What is the true identity of the enigmatic entity calling itself "the Count"?

As Chaldea was holding a strategy meeting on the subject of how to combat this Count, an emergency alarm sounded throughout the ship. The alert was triggered by the Heroic Spirit Summoning System activating on its own. The system summoned a single Servant, then fell silent once more.

"We meet again, Master."

Master encountered the manifested Servant, but was immediately drawn into a deep slumber, as if falling into a dark abyss. When Master opened their eyes once again, they were greeted by a familiar cityscape under a gray sky and the route from home to school—sights taken from an everyday life that was fading into a distant memory.

The second out of 4 Ordeal Call chapters, focusing on the Avenger class.