Genjutsus

The man had been waving his kunai up at the sky for a while, before Itachi
finally placed a gentle hand on his back.
“You done yet?”
The man’s shoulders shot up, as though Itachi’s voice had awakened him
from a dream, and he whirled around.
“The thing you’ve been trying so desperately to cut in half is my genjutsu.”
“Wh-what ...”
“Do you want to have the dream again?” Both of Itachi’s eyes were a deep
red.
“Ee! Eee!” The man dropped his kunai and cowered the moment he saw
the sharingan. “H-have mercy!” he begged, tears streaming down his face.
Itachi’s eyes turned black again.

Book of Bright Light Chapter 2 Part 4