Naruto: I Reincarnated as Sakura’s Brother

William sat on a stone, observing the nature around him. He reflected on his training methods and realized that, despite his efforts, he still lacked technique and knowledge. The wind moved the treetops, creating a soft melody. The sound of leaves falling on the ground sounded like a distant whisper.

"The clearing was silent, except for the sound of the leaves softly blending with the wind and the distant song of a bird. The fresh morning air seemed to penetrate William's skin, as he remained still, absorbing every nuance around him.

He closed his eyes and felt the vibration of the wind through the trees, as if the world itself were breathing with him. Each leaf that touched the ground, each small movement in the air, seemed to amplify. The light touch of the dry leaves on the ground beneath his bare feet became valuable information, a clue as to where danger might come from."

"If I can understand how these animals have such sharp senses, maybe I can develop my own technique to locate and track my target, shooting arrows at distances where I can't even see the target."

At the age of four, William decided to focus on training his reflexes and senses. He created a rustic bow, since there was no history of archers in his family. Being a novice with a poorly made bow, his arrows were imprecise, and he still couldn't hit animals with the accuracy he desired.

Aware of his "neutral" nature in the Naruto world — especially compared to the development of his sister in the original anime series — William spent a lot of time thinking about how best to train and sharpen his senses.

"I wonder what I'd be in this world if I didn't have this memory… What could I do? I don't have the fighting power that some ninjas have, but... maybe that's an advantage. Maybe I can use my intelligence, my observation, to be useful in another way. Sakura is strong, but she still doesn't have control over her fate.

I can't be like her in the beginning, without any means to react. I need something that makes me valuable. I won't be just another shadow in this world. I will be a ninja, but a ninja who works in the background, who acts when no one's looking, who senses danger before being seen."

He was preparing not to be useless like his sister was in the beginning of the series, planning to become a support ninja. The idea was to be a sensor, medic, and support, staying in the background and attacking with his bow when the opportunity arose.

William: "This isn't enough. I thought that living in the wild, observing the habits of animals, especially predators, and even hunting them... The ancients did this because it was part of their lives. But I need more. I need adaptability, technique..."

Inspired by the anime Kimetsu no Yaiba, William began to consider developing a breathing technique to enhance his body and physical condition. He knew he wouldn't have access to specialized taijutsu methods; in fact, he hadn't even been taught the academy's basic katas yet, much less training like Guy's Eight Gates. So, he decided to create his own training method, in the best Onee Puuuunch! style (hoping, of course, not to go bald).

His usual training began with some physical exercises: squats, push-ups, sit-ups, military-style crawling, and camouflage to try to catch unsuspecting animals. He would push himself until partially exhausted and then begin practicing meditation while working on his breathing technique.

"Breathing is more than just a physical trick. It's the key to unlocking my body. If Tanjiro can increase his strength and endurance with breathing, maybe I can too. But I can't do it just any way. I need to expand my breathing capacity, increase my blood flow, and maybe, just maybe, I can use this technique to push beyond my limits. Can I achieve something more, something beyond?"

"Tanjiro used the Total Concentration technique to fight demons. If I can adapt this technique to my training, not only would my physical abilities improve greatly, but by adding some defensive jutsu, I would become less defenseless. After all, sometimes it's not bad to be like a turtle... In this case, a Ninja Turtle."

"But, regarding Tanjiro's Water Breathing technique, I'm more inclined toward the neutrality of Inosuke's Beast Breathing. The nature of the mountains and forests were his masters, and they taught him everything."

"Expand my lungs, accelerate my blood flow, and raise my internal temperature. This will help me get stronger. I need to practice every day. I'll perfect this training set that will fill in my weaknesses and help me achieve my goals as a ninja in this new world."

"Inosuke's breathing... It's not gentle, nor precise, but it's instinctive. Fierce. Wild. Maybe this is the key: connecting with raw nature. If I can connect with the strength of the mountains, with the wind, with the sounds of the forest... maybe I'll sense something no ordinary ninja could. But this goes beyond simple breath control. I need to surrender to nature, be like it: unpredictable and untamable."

"Also, I'm attracted to this technique because the more I connect with nature, the more I might connect with the main storyline of this world. Characters like Juugo, who naturally have an affinity with Sage Arts, and maybe even be discovered by one of the three Sannin of Konoha... Hmmmm, it would be great if a cute kid like me were suffocated to death in the two wonderful mountains known as Tsunade."