"Fire Style: Phoenix Sage Fire Technique!"
Sasuke Uchiha's hands rapidly formed seals, and several fireballs flew out, braving the light rain.
Interestingly, Itachi Uchiha used the exact same ninjutsu. It was unknown whether this was to test his younger brother's capacity or for some other reason…
"Don't you feel something is a bit off?" White Zetsu asked.
"Perhaps he wants to force Sasuke Uchiha to awaken the Mangekyo Sharingan," Black Zetsu said, words he himself didn't quite believe.
It was common knowledge that the only way for an Uchiha to awaken the Mangekyo Sharingan was to kill their closest kin; this was a curse stemming from the depths of their bloodline.
If the Mangekyo Sharingan could be awakened merely through a battle, the Uchiha clan would have conquered the shinobi world long ago.
"Where's Kisame?"
"He returned to the base."
Clang, clang, clang!
Several sparks flashed.
Sasuke Uchiha looked at the three-tomoe Sharingan in his opponent's eye sockets, a trace of doubt flickering in his own eyes.
Why wasn't he using the Mangekyo?
In a battle of three-tomoe Sharingan, he didn't believe Itachi was his match. After this period of growth, he was no longer the weakling he once was, the waste who could only weep over his parents' corpses.
Crackle!
Chidori Nagashi coated his blade. The suddenly expanded attack range slashed open the Akatsuki's black-and-red-cloud-patterned uniform, revealing the black ninja chainmail underneath.
"Where is your Mangekyo?" Sasuke Uchiha taunted. "Let me see your true capacity."
"The capacity you were willing to kill Mom and Dad to obtain."
As he reached the end of his sentence, his tone was already filled with fury, and the electric light in his hand intensified severalfold.
"Yes! Very good!" Sensing his anger, Itachi Uchiha revealed a very satisfied expression. "That's it, resent me! Hate me!"
"Channel all these emotions into the pupil power of your Sharingan! My foolish little brother!"
Suddenly, Sasuke Uchiha felt the world around him twist and change. When he came to his senses, he found himself in a dark red space.
Even more bizarrely, his body was bound to an iron cross, unable to move.
"Demonic Illusion: Shackling Stakes Technique!"
The name of this ninjutsu surfaced in his mind; it was a dōjutsu-based genjutsu unique to the Uchiha clan.
"Itachi, I'm different now!" Watching the man slowly materialize before him, the three-tomoe Sharingan in Sasuke Uchiha's eyes spun rapidly.
The mere Shackling Stakes Technique, to him now, he could break free with a wave of his hand…
"What's going on?!"
Sasuke Uchiha stared in shock at the iron chains still binding him to the cross.
"This is Tsukuyomi, an ability unique to the Mangekyo Sharingan," Itachi explained, seemingly sensing his confusion.
"Didn't you want to witness my capacity?"
"In the world of Tsukuyomi, all factors, including time, place, and mass, are under my control. Within this space, all the pain you endure is no different from reality."
"Argh!" Watching helplessly as Itachi Uchiha plunged an iron rod into his body, feeling the pain that pierced deep into his marrow, Sasuke Uchiha let out a wail of agony.
"Your next seventy-two hours will be spent in this space." At this moment, Itachi Uchiha's calm voice was, to him, no different from the most terrifying thing in the world.
Often, what made a victim feel terror was not the physical pain itself, but the torment of the punishment slowly descending upon their body.
"Aaargh!"
Immediately after, two more iron rods were thrust into his body.
"One second has passed."
Itachi Uchiha's figure duplicated from one to two; four iron rods were then thrust into Sasuke Uchiha's body.
"Aaaaargh!!!"
"Two seconds have passed."
The dual torment of mind and body caused Sasuke Uchiha's gaze to start becoming unfocused.
Within this Tsukuyomi space, with every second that passed, Itachi Uchiha's figures would double; the iron rods piercing Sasuke Uchiha's body would double; the sound of his screams would double in intensity…
Outside.
"Why have they both stopped moving?" White Zetsu looked with confusion at the two figures frozen in place.
"Itachi Uchiha has started getting serious. This is Tsukuyomi, a unique ability of the Mangekyo Sharingan, the world's most powerful spiritual attack," Black Zetsu explained.
"He moved!"
Both Zetsu focused their gaze. Sasuke Uchiha, who had been so imposing just moments ago, suddenly collapsed to his knees in a wretched state.
Itachi Uchiha, opposite him, wasn't faring much better. He clutched his left eye in pain, fresh blood slowly seeping through his fingers.
"Is this the price for using Tsukuyomi?" White Zetsu watched this scene with astonishment.
"Correct." Black Zetsu's tone was inscrutable. "Before fusing with Sasuke Uchiha's Mangekyo Sharingan to ascend to the Eternal Mangekyo Sharingan, every time Itachi Uchiha uses a Mangekyo ability, his eyesight will deteriorate."
"Sasuke…" Itachi Uchiha swayed as he walked towards his younger brother, his tone as if he wanted to devour him whole.
"You see my eyes, don't you? This is the price of using the Mangekyo Sharingan. It is about to lose all its light."
"To me, you are new light."
"Come, give me your eyes. Let my eyes evolve into the Eternal Mangekyo Sharingan."
"I will become the next Madara Uchiha. The Uchiha will, under my leadership, return to glory."
"You are not worthy to invoke the Uchiha name!"
Sasuke Uchiha, half-kneeling on the ground, abruptly looked up at him and roared in fury.
Countless eerie, dark purplish patterns spread from his left shoulder across his entire body. When these strange patterns covered most of him, Sasuke Uchiha's physique began to develop in an inhuman direction.
His skin turned dark, a blackness like that of a hell demon. A pair of menacing, hand-like wings unfurled from his shoulder blades.
A pitch-black cross mark was imprinted on the bridge of his nose.
Dark purplish Chidori Nagashi enveloped his palm as he viciously stabbed towards the enemy before him.
Thud!
Several dark red skeletal ribs encased Itachi Uchiha, helping him block the Chidori Nagashi attack.
"This is—!" Sasuke Uchiha's pupils contracted. A sense of crisis welled up in his heart. With a flap of his wings, his figure rapidly retreated.
From the dark red skeletal structure, a skeletal hand had, at some point, emerged, smashing down heavily where he had just been standing.
BOOM!!
A large amount of rubble obstructed the two's line of sight.
"Such terrifying chakra?!" White Zetsu's pupils shrank.
"This is Susanoo, the pinnacle of Uchiha power. During the Warring States Period, it was known to the world as 'God's Power'!" Itachi Uchiha spread his arms wide, laughing wildly and unrestrainedly.
"My foolish little brother, the power you obtained from Orochimaru is utterly insignificant before Susanoo."
"The best path was right in front of you, yet you ignored it!"
"Where are your Konoha comrades? Where is the teacher you respected? Why didn't you kill them?" Itachi Uchiha questioned.
"This power, comparable to that of a god, was clearly within your grasp."
"Your capacity… truly stops here…"
"Shut up!!" Sasuke Uchiha roared.
"Your path, I scorn to tread!"