“You guys—!” They should be saving the injured. Kamijou understood this fact and was unable to maintain his silence. He inadvertently attempted to grab the shoulder of a nearby student. “—WHAT ARE YOU DOING? HURRY UP AND CALL AN AMBUL—”

However, Kamijou stopped.
Kamijou’s hand was forcefully dragged forward.
No.

Dragged was inadequate. The force he felt was like attempting to grab the driver’s side door of a moving truck. The magnitude of the propulsion was completely different.

“WHA—!”

His arm was nearly dislocated. The true shock was that the student had not acted at all. Kamijou’s hand on that shoulder felt like a balloon tied to a car. What was more, the person seemed completely ignorant Kamijou’s roar let alone his hand.

Before them, Kamijou was like the twisted suit of armor.

“…What’s going on?” Kamijou recalled the sensation his hand experienced. While he expected the texture of soft fabric clothing, his hand felt like it passed through extremely hard glue. Forget the student’s shoulder, Kamijou could not reach the clothing.

“It’s a boundary like the two sides of a coin. The students are on the ‘front of the coin’ and can’t detect those of us on the ‘back of the coin.’ We, the intruders on the back, can’t interfere with the people on the ‘front’ who are ignorant. Look.” Stiyl spoke like he was chanting and raised a finger to point at a girl walking out of the elevator.

Kamijou’s eyes followed the girl’s back. She stepped into the blood but her shoes were not stained and left no bloody footprints. The pool of blood acted like one large sheet of hardened plastic.

Toaru Majutsu no Index vol.3 ch.2 pt.3