one thousandth of a second

On the other side, Kanzaki needed no preparation. All she had to do was lightly touch
her finger to the hilt of the long katana that hung from her waist. She wove magic power
within her body using a certain type of unique breathing method, then reconstructed her
own body into the “Breaker of God”.
Then there was silence.
After that silence, which was so short—one-thousandth of a second—that a human
couldn’t detect it...
Power of God and the Breaker of God began their bout of life and death.
A powerful bellow could be heard.
It was the sound of Kanzaki, ten meters away, cleaving through the fifty-meter water
wing that the archangel brought down on her head.
However, Power of God did not move, for it could mend its shorn wings however many
times it needed to. Before Kanzaki replaced her katana in the sheath and regained her
balance, it waved another wing toward her for a strike from the left side.
As soon as Kanzaki cut that one apart, another wing flashed across on the right, aiming
for her back.
There was a distance of ten meters between Power of God and Kanzaki. The angel
seemed to be trying to maintain that distance. It repeated its flurry of wing attacks, not
letting Kanzaki draw near.
Kanzaki twisted her whole body, turned around, and cleaved the wing coming at her
back in two. As if aiming for that moment, the servant of God swung three watery wings
down on her from directly overhead, leaving time gaps between each.
The time gaps, however, were one-hundredth of a second—the realm of godlike speed, a
gap undetectable by humans. However, Kanzaki reacted to it. The human body
apparently needs 0.18 seconds to deliver a command from the brain to the fingertips,
but Kanzaki, having transformed into the Breaker of God, was temporarily in a state
above human domain, and that kind of common sense wouldn’t work. Her blood vessels,
muscles, nerves, organs, and skeleton—they were all recomposed so that they were able
to kill gods due to the technique she used.

Kanzaki sliced through the first of the three watery wings by unsheathing the katana.
Before the next one-hundredth of a second elapsed, Kanzaki already had swung the
Shichiten Shichitou back in its sheath and was prepared for the next strike.
She even smiled a bit, since she had time to spare that one-hundredth of a second, but at
that moment—
The second watery wing spontaneously shattered.

- Toaru Majutsu no Index Volume 4, Chapter 3 Part 5