Without hesitation, Sasuke sat cross-legged on the bed and began controlling the chakra in his body, compressing it relentlessly.
"Sasuke, are you asleep yet?"
Mikoto was outside Sasuke's bedroom door, holding a tray in one hand with steaming hot food, while lightly knocking on the bedroom door with the other.
"Oh, not yet." Interrupted in his training, Sasuke had to get up and open the door. Checking the clock, he realized that two hours had already passed. In those two hours, although he hadn't managed to compress his chakra into liquid, he'd still made some progress: one percent of his blue chakra had been pressed into a deep blue. His chakra had increased a bit. That proved his method was correct.
"Sasuke, you skipped dinner, so I was worried you might get hungry tonight. I made you a little something to eat,"
Mikoto said as she walked in.
"Oh, thank you," Sasuke replied, his face full of gratitude as he took the tray.
"Silly child, I'm your mother, you know."
Mikoto smiled as she gently patted Sasuke on the head.
Setting the tray on the table, Sasuke ate silently while Mikoto, seeing him quietly eating, turned away and began tidying up his messy room.
Watching Mikoto silently clean his room, Sasuke's heart was filled with warmth, but deep down there was still a tinge of worry and gloom. When Sasuke had been born, he'd told himself not to grow attached to anyone in the Uchiha clan. They would all die. But from the moment he was born till now, Sasuke had always been surrounded by Mikoto's love. This omnipresent care slowly melted Sasuke's resistance and made him accept Mikoto—and treat her as his true mother. After all, people aren't cold-blooded: when someone is good to you, it's impossible to stay unmoved.
Sasuke knew that, on a certain day three years from now, the currently powerful Uchiha clan would be wiped out in a single night by Itachi Uchiha and Tobi working together. Apart from himself and Itachi, not a single member of the Uchiha clan would survive. That meant the loving mother before him would also...
"No."
Sasuke said to himself: The lives of others may not concern me, but Mikoto Uchiha—I won't allow anyone to harm her. If anyone even tries, I'll make sure they regret ever coming into this world.
"Sasuke, if you're done eating, go get to bed early, alright!"
Mikoto finished tidying the room, noticed Sasuke had finished eating, cleared the dishes away, and left the room.
Watching Mikoto's departing figure, Sasuke silently renewed his vow: Itachi, I'll never allow anyone to hurt mother.
"Looks like I have to intensify my training. Who knows how strong I'll be three years from now?"
Sasuke once more sat on his bed, preparing to compress his chakra.
The next morning, after finishing his training, he was utterly exhausted—he simply couldn't go on. Collapsing onto his bed, Sasuke fell asleep the instant he lay down.
When he woke up, it was already evening. Mikoto had come in twice to check on him; seeing Sasuke sleeping soundly, she'd quietly left the room again. Itachi had been sent on a mission early in the morning.
Upon waking, seeing that his method was working, Sasuke felt happy: overnight, he'd managed to compress one-twentieth of his blue chakra into deep blue. Even though he hadn't turned it into liquid chakra, he was still pleased. If it were too easy, it wouldn't be believable—only difficulty would prove chakra could truly multiply.
Because he hadn't fully succeeded yet, Sasuke limited himself each day to practicing "Fire Release: Great Fireball Technique" and "Lightning Release: Ground Stream," saving all his remaining chakra for compression.
A month passed.
For an entire month, Sasuke compressed his chakra in his room, blue chakra compacted into deep blue, replenishing it whenever it was spent. By the end of the month, his entire Chakra Pathway System was filled with deep blue chakra. The color even had a hint of black, indicating the density had reached a certain level. He was just one step away from compressing it into liquid chakra.
Sasuke was amazed to discover that now, whenever he recovered chakra, it was automatically deep blue, without needing him to compress it further. But when he performed ninjutsu, the chakra would turn blue again. In effect, his chakra was now more than double what it had been before.
Having more than twice as much chakra as before, Sasuke was overjoyed. Now he was wondering—he hadn't even achieved liquid chakra yet, and his reserves had already doubled. He was truly excited to see what would happen if it actually became liquid. Unable to resist the temptation, Sasuke began compressing chakra once again. "Ugh!"
Just as before, Sasuke found his strength was too weak—he just couldn't compress gas chakra into liquid.
"Looks like I need outside help. Time to find Itachi. Luckily, he's home today and not off on a mission."
Thinking this as he walked toward the door, Sasuke called out, "Brother, I need your help."
He approached Itachi, who was reading a scroll. "Oh, it's Sasuke. What's up?" Itachi put down his scroll and looked up at Sasuke, waiting for the question. Sasuke didn't say anything, but grabbed Itachi's hand and pulled him out to the Training Ground. "Sasuke, wait up!" Itachi called as Sasuke led him on; he had no choice but to put down his scroll and hurry after him.
"Brother, here's the thing..." Standing on the Training Ground, Sasuke told Itachi everything.
"What?!"
After listening, Itachi couldn't hide his surprise. He immediately placed both hands on Sasuke's shoulders. After a moment, "Amazing—I never thought you'd come up with something like this. But using my power for this carries risks, Sasuke. Make sure you understand that."
Itachi took his hands away, speaking solemnly.
"I understand, but I have to try,"
Sasuke replied firmly.
"Alright, but if anything dangerous happens, you must stop immediately," Itachi said, still full of concern.
"Mm," Sasuke answered halfheartedly. In reality, this method could only be used by him alone. If Itachi tried compressing his chakra, it would be far more trouble than it was worth.
First, Itachi, with Chunin-level chakra, would take who knows how long to compress it. Sasuke, with far less chakra, needed a whole month.
Second, the older you get, the more impurities accumulate in your chakra. More impurities mean more time to compress—and it might not even turn into liquid chakra at all. Liquid chakra could only be achieved if the chakra was completely pure.
If Itachi spent several years compressing his chakra, only for it to increase by one or twofold, he'd be better off just learning a few stronger ninjutsu. A ninja's power isn't measured just by chakra alone.
As for other kids, it wouldn't work either. At age three or four, even producing chakra is a sign of genius—how could they possibly control it enough to compress it? Not to mention that compressing chakra is extremely taxing mentally. At that age, a child is only just learning the basics, and their mind is still very weak. So this method could only be used by Sasuke, who had already lived an entire life.