The safety of Kushina Uzumaki, the Second Jinchuriki of the Nine-Tails, was of paramount importance to Konoha. Ever since the tragedy that befell the Land of Whirlpools and the decimation of the Uzumaki Clan, ensuring that a surviving Uzumaki could thrive became a top priority. Now, with Mito Uzumaki advanced in years and less capable of defending her family, the responsibility fell to the village itself.
Hiruzen Sarutobi, ever the wise strategist, had devised a plan to pair Kushina with Aosui. Aosui was an ideal partner—not only was he without a teammate, but he and Kushina had also formed a strong friendship over time. Beyond familiarity, Aosui's combat strength was unquestionable; he could protect Kushina from almost any threat, even in the midst of the most dangerous missions.
"Alright, alright, I understand. I'll tell Kushina tomorrow," Aosui said, finally agreeing after Tsunade's insistence. "If there's nothing else, I'm going to rest now."
Tsunade's expression was impatient but resigned. Hiruzen, sitting beside her, shook his head with a faint smile, knowing that late-night discussions could only go so far. The hour was late, and even the wise Hokage needed rest.
After escorting Mikoto back to the Uchiha compound, Aosui returned to his home. There, he wasted no time before performing a Summoning Jutsu. A small, palm-sized slug materialized before him, blinking up at him curiously.
"Lord Aosui, is there something you need at this hour?" the slug inquired, its voice both gentle and inquisitive.
"Yes, Slug Sage. I have been studying the Sage Arts of the Three Great Sage Regions, and I wanted to ask you about them," Aosui said eagerly. He had been thinking about this for a long time. The Sage Arts were powerful techniques, the pinnacle of natural energy mastery, and he was determined to understand them fully.
The slug's tiny body shimmered slightly, a faint aura of wisdom radiating from it. "Lord Aosui, learning Sage Art is not simple. With your current chakra, you can barely manage it."
Aosui froze for a moment. He had already amassed nearly eighty thousand chakra points, an amount surpassing that of most ninja in Konoha, yet the Slug Sage implied that even this was only barely sufficient. It was no wonder that only a handful of ninja throughout history had successfully mastered Sage Art.
"The natural energy… it's dangerous?" Aosui asked, his voice tinged with concern.
The Slug Sage nodded. "Yes. The energy of the world is highly corrosive to those unprepared. If a ninja attempts to absorb it without sufficient chakra, the energy will overwhelm and consume them. Many have perished in the attempt, leaving nothing but bones behind. The forest of Shikkotsu is named for these remains, the failures forming a macabre 'bone forest.'"
Aosui swallowed hard. He could vividly imagine the countless ninja who had tried and failed before him. The method of cultivating Sage Art in Shikkotsu Forest was far more dangerous than the paths at Mount Myōboku or Ryūchi Cave. On Mount Myōboku, failures turned into stone frog statues—a grim fate, but not immediate death. Here, those who failed became part of the forest itself.
"So, how does one cultivate Sage Art in Shikkotsu Forest?" Aosui asked, forcing himself to remain calm despite the fear curling in his chest.
The Slug Sage smiled faintly, though its eyes betrayed a hint of mischief. "It's simple. Endure my acid, and you can learn Sage Art."
Aosui froze. "Your acid?"
The slug nodded. "Yes. It is corrosive, lethal to the unprepared, yet it is one of the few ways to attune your body to natural energy. Only the strongest, with exceptional self-healing abilities, have ever survived this trial."
Aosui's mind raced. The sheer danger of this method was staggering. It was no exaggeration to say that only someone with superhuman resilience could attempt it. Compared to Mount Myōboku's training or Ryūchi Cave's methods, Shikkotsu Forest demanded an entirely different level of fortitude—both mental and physical.
"Has anyone ever survived this method before?" Aosui asked cautiously.
The Slug Sage pondered, then replied, "If I recall correctly, one individual did, several centuries ago. He had extraordinary physical strength and an unparalleled healing factor. Without these attributes, the trial is a death sentence."
Aosui exhaled slowly, a mix of awe and fear settling over him. He realized now why Tsunade, despite her legendary prowess, had never attempted the Sage Arts at Shikkotsu Forest in her youth. At that time, she had not yet mastered the Yin Seal nor developed the Strength of a Hundred Seal. She simply lacked the requisite power and experience.
Even if Tsunade had later gained the necessary skills, her focus had shifted. By the time Jiraiya and Naruto convinced her to return to Konoha and take the mantle of Hokage, the luxury of intensive Sage training was no longer feasible.
"So, Lord Aosui," the Slug Sage said gently, "do you still wish to pursue learning Sage Art?"
The tone was gentle, almost playful, yet Aosui felt as if the Grim Reaper himself had spoken. Swallowing hard, he replied, "I… I only wished to learn more about Sage Art. For now, I have no plans to attempt it myself."
The Slug Sage's voice was kind, yet filled with authority. "You can learn anything you wish, Lord Aosui. Knowledge is always within reach. You need only ask."
Aosui's curiosity overcame his fear. "Then… could you tell me how you mastered Sage Art?"
The Slug Sage's eyes gleamed. "Of course. I will recount my methods in detail, and answer every question you may have."
For the remainder of the night, Aosui listened intently. The Slug Sage described its experiences, detailing the process of attuning one's body to natural energy, the dangers encountered, and the precautions necessary to survive. Aosui asked questions, probed deeper, and absorbed every lesson like a sponge. By the time dawn began to lighten the horizon, he had gained invaluable knowledge, as well as a safe and effective approach to studying Sage Art independently.
"Thank you, Slug Sage," Aosui said sincerely, bowing slightly.
"It is nothing, Lord Aosui. Should you require assistance in the future, summon me at any time," the slug replied. With a gentle shimmer, it disappeared, returning to Shikkotsu Forest.
The night had passed, and Aosui felt a renewed sense of purpose. Although he had not physically trained in Sage Art, the knowledge he gained provided a critical head start for future research and potential mastery.
"Time to head to Konoha Hospital," Aosui murmured to himself. Though he had not slept, a single sleepless night was trivial for a ninja. He was accustomed to performing long missions without rest, and his stamina and training ensured he could continue without adverse effects.
Upon arriving at the hospital, Aosui was greeted warmly. "Ah, it's Lord Aosui! Long time no see!" one nurse exclaimed. Others echoed the sentiment, delighted to see him after more than half a month.
"Long time no see, everyone," Aosui replied with a small smile, settling into his office. He retrieved a scroll and began recording his observations on Sage Art, ensuring every detail was preserved for future reference.
A knock at the door interrupted him. "Lord Aosui, a patient requires your immediate attention," a nurse said urgently.
"Understood," Aosui replied promptly. "Prepare for surgery immediately. I'll be there."
With focused precision, Aosui attended to the patient, successfully completing the treatment of Seitaro Tanabe. As the system notified him, he received feedback and a reward:
[Completed the treatment of Seitaro Tanabe, rewarded with a blue orb.]
[Congratulations on obtaining 100 chakra points.]
Aosui allowed himself a brief moment of satisfaction. Every step, every lesson, and every mission brought him closer to understanding his own potential—and to mastering the formidable powers of Sage Art.
Advance Chapters avilable on patreon (Obito_uchiha)