"Hoo..."
As if he'd heard the wind, Sasuke Uchiha instinctively turned and looked up at the sky.
The summer afternoon sun blazed overhead. White clouds drifted across it like frilled hems, and the sharp glare made him raise a hand to shield his eyes. Cicadas buzzed without pause in the heat.
Probably just the wind.
Crunch. He took another bite of watermelon. The sweetness was cool and refreshing, and his gaze drifted quietly toward his mother, who was busy at work in the yard.
Knock knock knock!
Someone was at the door. His mother quickly set down what she was carrying and hurried over to answer it. A moment later, a muffled conversation floated in from the entryway.
"So it's Shisui..."
"...Is Itachi home?"
"He left on a mission this morning. He probably won't be back for a few days..."
Sasuke tossed aside the watermelon rind, wiped his mouth carelessly with the back of his hand, then glanced around by instinct. Even without his father there to give him that disappointed look, he still obediently took out a handkerchief and cleaned his hands and face properly before padding soundlessly into the hallway.
The visitor was Shisui Uchiha, his brother's friend.
He'd heard Shisui was even more of a genius than Itachi.
Sasuke looked up at Shisui's gentle, smiling face.
"!"
Shisui suddenly turned his head, startling him. Sasuke still managed to keep a calm expression and put on a polite smile.
In return, he got an especially warm look.
"I'll come by another time. Please excuse me for now." Even Shisui's voice was soft and easygoing, nothing like what Sasuke imagined a prodigy would sound like. As he spoke, he discreetly winked at Sasuke and mouthed a silent goodbye.
[If I were as strong as my brother... and him... then Father would definitely have high hopes for me too.]
Sasuke's heart filled with longing.
"Haaah..." For some reason, he suddenly felt drowsy. He yawned, stumbled back into the living room, sat down against the tatami, and before long drifted into a deep sleep.
---
You foolish little Sasuke.
Arata looked at his innocent host and sighed helplessly.
As a native of Earth, he'd imagined countless times what it would be like if he were ever transmigrated into another world. He had never expected his first shot would drop him into the familiar world of Naruto. Two joys stacked together should have meant even greater joy, but in all his fantasies, he had never once imagined he'd end up transmigrating as a lump of chakra.
More specifically, Indra's chakra.
The reincarnated chakra.
The exact mass of chakra that, in the manga, clung to Sasuke all the way through and eventually became the channel old Sage of Six Paths Grandpa used to hand Sasuke a late-game power-up.
At this point, Arata didn't even know what species he counted as. Something in the same category as a tailed beast, maybe?
Still, he was here now. He'd always been the easygoing type anyway. Since things had already turned out like this, what was the point in cursing the Gods?
The only problem was that, unlike a tailed beast, he seemed completely unable to survive on his own as a chakra life-form. The moment he left his host, he started to dissipate. He'd tested it right after arriving. The second he flew out, his chakra body began to come apart. There was no way he was gambling on whether he'd still be alive after the chakra making up his body scattered, so he shot back into his host at top speed.
After that, he'd occasionally slip out for a quick wander before ducking back inside.
Based on his own experiments, if he stayed outside a host for more than two minutes, his structure would collapse back into pure chakra, no longer stable enough to support his consciousness. He needed Uchiha blood to hold himself together.
He had tested that too. An Uchiha who hadn't awakened the Sharingan could only support him for a few seconds. An Uchiha with a one-tomoe, two-tomoe, or three-tomoe Sharingan could host him anywhere from a few dozen seconds to a few minutes.
As for the Mangekyo, he had never tried.
He just had an instinctive feeling that if he tried to inhabit someone with a Mangekyo Sharingan, they would notice him.
At present, only Sasuke could host him without any time limit. As expected, the person chosen to become the reincarnation of Indra's chakra really was different.
If he lost half the chakra that made up his body, his consciousness started to blur. Once he returned to an Uchiha body, it took about an hour for all of it to recover.
In short, Arata had spent more than a year living quietly in Konoha as a chakra life-form. Thanks to the fact that no one could detect him, he had learned a great many things. If he'd had a proper body, he would have been unstoppable by now. Sadly, he didn't. Without a body, all that potential was useless.
Which meant he had no choice but to step into the spotlight and deal with a few problems himself.
For example, the Uchiha massacre.
The reason was simple.
As long as the Uchiha were alive, he could use clan members as stepping stones and stay active outside for fairly long stretches of time. If almost all of them died, wouldn't that mean he'd be stuck hovering around Sasuke forever?
And who knew whether Sasuke would even survive this time the way he did in the manga? Arata had no intention of transmigrating into another world only to put blind faith in manga canon.
A man had to hold his own fate in his own hands.
"The Uchiha district. Uchiha corpses. Fugaku and Mikoto Uchiha. Itachi Uchiha. The pieces are in place..."
Bit by bit, Arata wove together illusion and perception. Once everything was complete, he cast the genjutsu he called Night of the Massacre.
"The stage is set. The cast is in position. Time for a nightmare."
"Sasuke."
He watched Sasuke's consciousness sink into the illusion and began taking over the body's neural signals.
As everyone knew, genjutsu worked by invading the enemy through the five senses and producing illusions by manipulating the chakra in their brain.
Most of the time, it was used as support. After all, genjutsu didn't have direct killing power, and any ninja with even a little real experience knew how to disrupt their own chakra and break free.
Breaking a genjutsu by scrambling your chakra had basically no barrier to entry. Even a genin could learn it. But learning genjutsu itself was tedious. It required specific talent, and using it properly took brains. Otherwise, once the target noticed anything was wrong, they could break it at any moment. Using it well was genuinely difficult.
A non-doujutsu genjutsu user without a brain was basically handing themselves a life sentence.
But thanks to the Sharingan, any Uchiha who awakened it stood at the very top of the ninja world in both genjutsu use and resistance.
On the battlefield, it was common knowledge that if you ran into one Sharingan-using Uchiha, you ran. If you ran into two, you ambushed them or prayed.
But Arata, a sentient mass of chakra, could proudly say this:
No "person" was better at genjutsu than he was.
Other people had to fight tooth and nail to invade through the five senses. He only needed to say, I'm in, and then he could start interfering with and controlling chakra directly.
As a life-form made entirely of chakra, his control over chakra was as natural as moving his own hands and feet. With just a little practice, he could achieve a level human beings could spend their whole lives chasing and never reach. As for talent in genjutsu, humans simply couldn't compare.
Unless it was an extremely high-level genjutsu like Tsukuyomi, which created an actual mental world, every illusion had some kind of flaw.
That was why low-level genjutsu tended to be simple and blunt, stirring emotions directly, or blending into the environment to create slight interference. Higher-level genjutsu usually focused on controlling the target's body through chakra manipulation, using minor illusions only as support to achieve the real goal.
Take the B-rank Tree Bind Death, or A-rank jutsus like Bringer-of-Darkness and Temple of Nirvana. The people caught in them usually knew perfectly well they'd been hit by genjutsu. They just couldn't move, couldn't see, or had been forced asleep.
The illusion itself was almost abandoned entirely.
What mattered was restricting the body and disrupting action.
Actually fighting through layered illusions had become more or less an Uchiha specialty. Just look at battles like Itachi against Sasuke, where both sides repeatedly used illusions to interfere with the flow of combat.
The main reason was simple: the Sharingan gave too much of a boost to genjutsu. Without it, there was no way to create an illusion without flaws. In the end, the logic became: if people were going to notice anyway, you might as well focus on disrupting the body instead.
Add in the low barrier for dispelling genjutsu, and non-doujutsu genjutsu ended up in an incredibly awkward spot.