My mentor was silent.

He walked along the road at a brisk pace, past the brick buildings, blooming vines, and rays of winter sunlight.

I noticed that the number of pedestrians were decreasing gradually as we passed through the street that seemed to never change.

It was different to when Lord Eulyphis had appeared yesterday. The people had not suddenly vanished unnaturally. It was more like they had just gradually tapered away.

“Sir?”

“…It’s a bounded field,” my mentor muttered. “But it doesn’t use Magical Energy. It’s a type of modern magecraft that affects people psychologically. Heartless is the former head of the Department of Modern Magecraft, after all. Though it’s essentially the same as what I did at Druid Street, the technique here has been thought out very well.”

“What does that mean?”

Before he responded, my mentor first took out a cigar from his case and lit it.

The instant the smell entered my nose, I felt like some part of my brain relaxed. I had only just realized how tired I had become.

“Like I discussed before in class, it’s a matter of feelings,” my mentor said with the cigar in his mouth. “It affects mages as well. Because no Magical Energy is involved, even mages that are considerably highly-ranked will have trouble detecting it. On the other hand, ordinary people can also detect it, but most people don’t have enough knowledge about bounded fields to recognize them.”

In other words, it was something that only someone like my mentor would be able to detect.

Lord El-Melloi II's Case Files: Grand Roll (Lower); Chapter 5, Part 6