Deep within the Gedō Mazō.
The black Ninja Beast Egg was suspended as if sealed by Drampa's bluish smoke, while Black Zetsu's agonized screams still echoed faintly from the shadows.
Crack.
The first fissure appeared on the egg's surface.
Black Zetsu's heart lurched violently.
The cracks rapidly spread,
the black shell peeling away layer by layer, dissipating like smoke in the air.
What emerged was a spherical black lifeform.
Semi-transparent, mist-like yet denser than mist.
Its main body was a deep black spherical substance, with purplish-black gas continuously drifting from its edges.
Large white eyes opened—small, yet keen and perceptive as if they could see into one's soul.
Its mouth split slightly, revealing two sharp little fangs.
Gastly.
The moment it hatched, the Gedō Mazō trembled as if instinctively repelled.
A faint, cloyingly sweet scent wafted through the chamber, so sickly sweet it made one's scalp tingle, yet carrying a strange gentleness from the depths of death.
Its form was indistinct, almost gaseous.
Inside the World Tree of another world.
[Gastly, Host: Black Zetsu.]
[Awakened Trait: Levitate!]
[Skills: Hypnosis, Black Gaze.]
Gastly's toxicity was potent; inhaling even a part of its body would cause immediate unconsciousness, making it extremely dangerous.
It would use its gaseous form to envelop prey, slowly injecting toxins through the skin to weaken them.
No matter how large the opponent, its lightweight gaseous body could wrap around and end its life.
Uchiha Madara opened his eyes, fixing his gaze on this newly born eerie existence: "You, are the embodiment of my will?"
Gastly opened its mouth, its voice ethereal, almost identical to Black Zetsu's tone: "Yes, Lord Madara. I am the shadow born from you."
How could this creature speak with the same cadence as him!
Then Black Zetsu suddenly realized something—his soul and consciousness seemed to have been split, a portion severed just moments ago.
It wasn't just the Ninja Beast Egg that had been separated, but a fragment of his own soul.
No wonder Gastly's voice was the same as his.
This thing... was actually a part of him?!
Gastly floated up, maintaining a smile like an elegant deceiver,
and nodded to Madara: "I understand your goal, Lord Madara. You need me to continue carrying out... the Eye of the Moon Plan, correct?"
Uchiha Madara narrowed his eyes: "Good. Since you've inherited a part of my will, it means you should understand your mission."
Faced with such arrogance from Uchiha Madara, Gastly replied without hesitation: "Of course. I will continue to steer the world toward true peace, letting all sink into the dream of the Infinite Tsukuyomi."
Black Zetsu, hidden in the shadows, nearly exploded with rage.
Those were the lines he had crafted to manipulate Uchiha Madara in the future!
Those were the lies he had meticulously woven!
But now, Gastly had perfectly replicated them.
Even the phrasing was more natural, more gentle, and more... believable than his own.
Gastly continued using his voice: "For this world, and for your unfinished destiny."
Uchiha Madara closed his eyes, satisfied:
"Good. From now on, you are the incarnation of my will, Uchiha Madara."
Black Zetsu fell silent within the shadows.
In a certain sense, Gastly was indeed him.
A purer, more flexible, and less restricted version of him.
He could not stop it.
Yet Gastly could not completely detach from him either.
A strange dynamic existed between the two, as he noticed Gastly turning its head to glance at Black Zetsu deep within the shadows,
revealing a meaningful smile before facing Uchiha Madara again.
History rolled relentlessly onward.
Several hours later.
Within the deep passage of the Gedō Mazō, the light was so dim it nearly devoured everything.
Gastly floated mid-air, its body trembling slightly as it emitted black-purple gas, like a wisp of smoke that might dissipate at any moment.
Just as it drifted past the twisted finger bones of the colossal statue, the shadows stirred faintly.
A distorted, shadowy face flowed out from the wall, like a despair-drenched half-body pulled from a swamp.
But Gastly tilted its head slightly upward before approaching, as if it had known he was there all along.
Black Zetsu's voice was cold as venom:
"...Who are you?"
Gastly gave a light, almost playful smile.
Gas drifted gently from the corners of its mouth.
"Me?"
It floated closer slowly, its eyes curving like crescent moons.
"I am a part of you. Your thoughts, your obsessions, your resentment, your purpose..."
It gently tapped its round face.
"All continue within me."
Black Zetsu froze for half a second but immediately sneered:
"Cut the nonsense. I've seen this trick before. What are you really?"
Gastly interjected softly, its tone gentle: "I am also Ōtsutsuki Black Zetsu."
The entire passage fell into instant silence.
Black Zetsu's pupils contracted to pinpricks.
"You... what did you say?"
Gastly's smile didn't fade, its voice even growing milder: "I said who you are, and I've stated my identity. We are both Mother's children."
Its large white eyes stared fixedly at Black Zetsu.
"Bastard, you have no right to call yourself Mother's child!"
Black Zetsu's expression darkened completely, countless black tendrils sprouting from the ground, walls, and ceiling,
lunging at Gastly like the claws of a ferocious beast!
"You abomination! How dare you spy on Mother!"
The air twisted instantly into dark, monstrous shadows.
Yet Gastly only showed a hint of resignation, its body swaying lightly.
In the next moment, it dispersed as effortlessly as smoke in the wind.
All the tendrils passed through it, striking nothing.
Black Zetsu roared: "Show yourself!!"
The black mist coalesced again, and Gastly appeared above him, speaking in a tone one might use to soothe a child:
"There's no need for such hostility, Black Zetsu."
It looked down at Black Zetsu's face, formed of hatred and obsession.
Its voice was so gentle it sent shivers down the spine.
"You and I are one, both parts of Mother, aren't we?"
It extended a small hand formed of gas, pointing gently at Black Zetsu's chest:
"Your pain, your obsessions, your mission... I understand it all."
Black Zetsu stared at him intently, voice trembling slightly:
"...What do you want?"
Gastly's smile grew even lighter.
"To fulfill Mother's unfinished plan with you."
It drifted lightly to hover before Black Zetsu,
and at an almost intimate distance, in its own voice—
which was also Black Zetsu's voice—whispered:
"Don't worry."
"I won't betray you."
"After all..."
Gastly's gas gently spread around Black Zetsu, as if embracing him:
"I am you."
Black Zetsu fell silent.
The shadow trembled for a moment but lacked the strength to attack again.
He understood clearly—Gastly was part of his soul.
Yet precisely because it was part of himself, Black Zetsu found it even more dangerous and terrifying.
During their locked gaze, Gastly employed Hypnosis and Black Gaze.
Squinting, Black Zetsu asked, "Are you trying to hypnotize me?"
"No, I only wish to make you understand—our abilities are the same."
Eerie, mysterious...
Such was Gastly.