An extremely deep, muffled sound rose from beneath the stairs, neither human nor mechanical.
It ricocheted through the stairwell, its frequency so low that Guy could feel the changes in air pressure through his ribs.
Then came a second sound-and a third.
After the three muffled thuds, the stairwell floor began to vibrate.
It was not an earthquake. The vibrations were rhythmic, each interval precisely identical, as though the heartbeat of some enormous creature were traveling up through the ground.
Neji recognized the rhythm without even activating his Byakugan.
"The vibration frequency matches the fluctuating pulses of the five containers in the Culture Tanks-Kabuto is starting something up in sync."
"He isn't starting up the containers." Chisen tapped his cane against a stair, its Rubber Tip making a dull thud against the concrete.
The sound rolled a few steps down the stairwell before the muffled pounding below swallowed it.
He heard the exact frequency of that heartbeat-like vibration-twenty beats a minute, precisely matching the pulse of the largest gland in the six-gland test subject from the southern mountains.
"He's activating the glands.
"The five extracted glands are being connected to some kind of external life-support system. Kabuto is supplying them with blood, oxygen, and chakra, keeping them fully active before implanting them into the vessels.
"That heartbeat-like vibration isn't a heartbeat. It's the life-support system's pulsatile pump imitating a heart, pumping chakra fluid into the gland tissue."
In the passage at the bottom of the stairwell, the four jinchuriki stepped forward simultaneously beneath the red emergency lights.
Their steps were so perfectly synchronized that they seemed to be pulled by the same invisible string.
Their faces were obscured beneath their hoods. Only the red glow of the four beads on their chests shone painfully bright in the dark red emergency