Fuuyu had to care about his non-biological sister's relationship, because Uchiha Mikoto would become Uchiha Fugaku's wife in the future. They would give birth to two children, Uchiha Sasuke and Uchiha Itachi.
Both children would become extremely powerful ninjas. Uchiha Sasuke was the undisputed pride of heaven, born with the chakra of Indra's reincarnation. Uchiha Itachi was even more formidable; in the future, he would single-handedly wipe out his entire clan on the night of the Uchiha clan massacre, leaving only Sasuke alive.
Uchiha Mikoto, the mother, would also be killed by her own son, Uchiha Itachi, that night.
Fuuyu naturally did not want to see such a future. He did not want Uchiha Mikoto to die this way, so he had to change the future.
The simplest and most direct way to change the future and reverse the Uchiha clan massacre was to prevent Uchiha Mikoto and Uchiha Fugaku from getting together, preventing Uchiha Itachi from being born.
Therefore, when he heard Uchiha Mikoto say that she didn't have much interest in Fugaku, Fuuyu felt relieved. He chuckled and said, "Nothing at all, haha. I was just asking. I heard that guy seems very popular."
"He is very popular within the clan. He awakened the one-tomoe Sharingan at the age of eight, making him an undeniable genius of the Uchiha clan."
"I even heard people say that he is already being groomed as the next clan head," Uchiha Mikoto said.
"Oh, he's that good?" Fuuyu pretended to be surprised.
"Yes, but he's a strange person, like an autistic child. He's not as cute as my little brother," Uchiha Mikoto looked up and smiled at Fuuyu.
"Hmm," Fuuyu nodded. Uchiha Fugaku was certainly a bit of an oddball. The problem wasn't just that he raised the "filial" son, Uchiha Itachi. The bigger issue was that as the Clan Head, Uchiha Fugaku did nothing while the Leaf Village high-ups and the Uchiha high-ups grew suspicious and antagonistic, allowing the situation to deteriorate until the whole clan was annihilated.
"You seem very interested in him. I'll introduce you to him another day."
Uchiha Mikoto's intention was simple: Fugaku was the genius of the Uchiha clan, and if Fuuyu could get along with him, he might have a better life in the Uchiha clan in the future.
"No way," Fuuyu shook his head like a rattle-drum. He didn't want any association with such a narrow-minded person.
Uchiha Mikoto was about to say something else, but Fuuyu cut in:
"Mikoto, hurry up and take your bath. You reek of sweat."
"You rascal!" Uchiha Mikoto scolded playfully, rolling up her sleeve as if she was about to teach Fuuyu a lesson.
But Fuuyu had already slipped into his room and vanished without a trace.
The next day, before dawn.
When Fuuyu woke up and climbed out of bed, he felt completely refreshed. The soreness in his body had mysteriously vanished.
Is this the effect of the Glint-Glint Fruit?
Fuuyu guessed this was the most likely possibility; his physical condition had never been this good.
"It doesn't matter," Fuuyu shook his head and changed out of his pajamas.
After a quick wash, he quietly left his house, chewing on a piece of bread.
Soon, he arrived at the academy's training ground.
The training ground was unusually empty and quiet.
Looking around, Fuuyu was a bit surprised because he saw another figure at the academy training ground. He recognized the person; it was his classmate, Senju Nawaki.
Fuuyu hurried over and saw Nawaki diligently practicing ninjutsu. It was clear his practice was effective. With practiced hand seals, he created several clones. Nawaki had completely mastered the D-rank Clone Jutsu.
"Hey, Fuuyu! I see you again. Are you here to train too?" Nawaki greeted Fuuyu enthusiastically.
"Good morning, Nawaki," Fuuyu nodded and smiled.
Nawaki was one of the only two friends he had at the academy. The reason they became friends was simple: both were the 'dead last' of their class. Nawaki was the more extreme case, having been held back for two years at the age of ten and still not graduating.
After a brief exchange of pleasantries, they began their respective training. Fuuyu started doing push-ups on the ground, while Nawaki continued practicing ninjutsu. They didn't disturb each other.
One hundred twelve, one hundred thirteen...
After consuming the Glint-Glint Fruit, Fuuyu's body seemed to have broken through some kind of restraint. Today, he easily surpassed his previous day's record.
Although he was pouring sweat, wetting the ground beneath him, his eyes grew brighter. Fuuyu could clearly feel himself getting stronger. He saw hope—the hope of protecting his family—and his heart was immediately filled with motivation.
So, Fuuyu gritted his teeth and pressed on, until his arms began to tremble, his joints protested with sound, and his body grew heavy, seeming unable to continue.
Two ninety-three, two ninety-four...
He wanted to push through to the three-hundredth push-up, but his body gave out. On the two hundred and ninety-ninth one, his arms suddenly went limp, and his body collapsed weakly on the ground, breathing heavily through his nose and mouth.
Fuuyu, though sprawled on the ground, laughed, because he had vastly surpassed his yesterday's self, breaking through his physical limits.
Just then, a pale, soft hand appeared in front of him. Fuuyu reached out, took the hand, and was pulled up from the ground by its owner.
The owner of the hand was Nawaki. After pulling Fuuyu up, he said with admiration, "Fuuyu, you're so amazing! You did that many push-ups in one go."
"You did about three hundred push-ups, didn't you?"
"Two hundred and ninety-nine," Fuuyu replied, though he was too exhausted to say more.
"That's incredible! When I become Hokage, I'll make you the head of the Leaf Village Military Police Force," Nawaki daydreamed proudly.
"You're an Uchiha, after all."
"Alright, thank you then, future Hokage-sama," Fuuyu smiled helplessly. This Nawaki was practically a carbon copy of Naruto, both in personality and appearance. The only difference was that Naruto had the ultimate cheat code of the Nine-Tails, while Nawaki wasn't so lucky; he was just an ordinary civilian player.
"Oh, by the way, Fuuyu, you're training so hard this morning. Will your body be able to handle the ninjutsu duel later?" Nawaki asked. This question had been on his mind for a while.
"Huh, what? A ninjutsu duel today? Isn't it tomorrow?" Fuuyu was taken aback. He didn't know anything about this.
"No, you got the time wrong. It's today," Nawaki said strangely.
"Then if you knew about the ninjutsu duel, why were you still practicing ninjutsu just now? Aren't you afraid of depleting your chakra too much?" Fuuyu asked.
"Fuuyu, did you forget that I'm from the Senju clan?" Nawaki puffed out his chest proudly.
"We Senju aren't great at much, but we have a huge amount of chakra!"
Fuuyu: "......"