Ren continued training after testing the Great Dragon Fire Technique.
Even before he exchanged Tajima's mission credits for the two scrolls, Phoenix Sage Fire's favorability had already been close to twenty-five. He only needed to perform the technique several more times before the system finally responded.
Ren planted his feet on the scorched training ground and swiftly completed the hand seals.
"Fire Release: Phoenix Sage Fire Technique!"
A cluster of small fireballs burst from his mouth.
Unlike the overwhelming Great Fireball or the concentrated Great Dragon Fire, these flames scattered in different directions. They weaved between the trees, curving around obstacles before striking several wooden targets Ren had placed across the training ground.
The final fireball hit the center of its target.
A familiar notification appeared.
[Phoenix Sage Fire Technique favorability +2. Current favorability: 26/100—Friendly]
The system interface shimmered once more as a second notification followed.
[Stage reward obtained: Physique +1]
[New Trait Unlocked—Explosive Shells: Your Phoenix Sage Fire Technique has become exceptionally agile. Its scattered fireballs will track enemies within range using faster and less predictable trajectories. Each fireball also possesses a chance to trigger a secondary explosion upon striking its target, making the attack considerably more difficult to evade or defend against.]
Ren's eyes brightened.
"Tracking and secondary explosions?"
He examined the wooden targets.
The original Phoenix Sage Fire Technique relied on numbers and unpredictable trajectories. It allowed the user to launch several smaller fireballs simultaneously, forcing enemies to divide their attention between multiple attacks.
With the new trait, those flames would no longer travel along simple paths.
They could pursue moving targets.
Even if an enemy blocked the first impact, the secondary explosion might break through their defense or create an opening for Ren's next attack.
"Not bad."
Ren formed the hand seals again.
This time, he deliberately aimed away from the targets.
The small fireballs scattered across the training ground, but shortly after passing the wooden posts, several flames curved sharply in midair. Their trajectories twisted from different directions, converging on the nearest targets.
Three impacts sounded almost simultaneously.
The first two fireballs left black scorch marks. The third suddenly expanded after contact, detonating with a sharp crack and blasting the upper half of the target into splinters.
Ren studied the damage.
The probability of producing an additional explosion was not particularly high, but in a real battle, even one unexpected detonation could be fatal.
More importantly, tracking made Phoenix Sage Fire far more useful against agile opponents.
An enemy might dodge the first attack only to discover that the flames had turned around behind them.
By comparison, Ren's progress with the Dragon Fire Technique was much slower.
Dragon Fire was a completely new conquest target, which meant he could not benefit from accumulated favorability or years of experience. He would need to build proficiency from the beginning.
The scroll also emphasized that Dragon Fire performed best when used with ninja wire.
Traditionally, a shinobi would attach wire to shuriken or kunai and use it to restrict the target's movements. The user could then release Dragon Fire along the wire, guiding the concentrated flames directly toward the trapped enemy.
If Ren wanted to master the technique completely, he would also need to improve his wire manipulation.
That was not necessarily a disadvantage.
Ninja wire worked extremely well with traps, swordsmanship, shurikenjutsu, and Fire Release. Becoming skilled with it would strengthen more than one part of his combat style.
After gaining Great Dragon Fire and unlocking Phoenix Sage Fire's new trait, Ren's Fire Release system had finally begun to feel complete.
Great Fireball provided overwhelming firepower and broad area coverage.
Great Dragon Fire served as a long-range precision strike capable of piercing strong defenses.
Phoenix Sage Fire supplied scattered attacks, pursuit, and unpredictable secondary explosions.
He could eventually improve its lethality even further by learning Phoenix Sage Flower Nail Crimson, which concealed shuriken within the flames.
Finally, Great Fire Wall gave him a defensive option capable of obstructing enemy attacks and controlling the battlefield.
He now possessed power, range, precision, pursuit, and defense.
For the immediate future, Ren planned to focus on raising the favorability of his Fire Release techniques beyond fifty. Once he accomplished that, his elemental foundation would become considerably more reliable.
Whether he should next prioritize close combat or Water Release could wait until Hatake Swordsmanship unlocked its first trait.
Ren exhaled the last trace of heated air from his lungs and stretched his shoulders.
"The Medical Corps assessment is in two days."
He was confident in his chances of passing. Tsunade's warning had still been unusually direct, however, and underestimating an examination she personally supervised would be foolish.
Ren also needed to help Rin prepare.
The Advanced Medical Class was far more difficult than the ordinary Academy curriculum. If the Ninja Academy's academic subjects were comparable to middle school, then the medical program was closer to specialized college education.
Students were expected to understand anatomy, toxicology, chakra pathways, battlefield triage, surgical procedures, medicine preparation, and the symptoms of numerous injuries and illnesses.
Some of the more advanced subjects could have qualified as postgraduate research in his previous world.
Even Ren could not claim to understand everything completely.
Rin was intelligent and hardworking, but she absorbed the material more slowly than he did. If she encountered an unfamiliar complication during the assessment, hesitation could cost her the qualification.
"I'll review the surgical procedures with her again," Ren decided. "Especially hemorrhage control and tendon repair."
He packed away the scrolls and left the training ground.
Two days later, the Medical Corps assessment began.
Ren and Rin stood inside one of Konoha Hospital's operating rooms, dressed in sterile gowns, masks, and gloves. Bright surgical lights illuminated the patient on the table, while the sharp smell of disinfectant filled the air.
The patient was a chūnin who had returned from the border with several metal fragments embedded in his thigh. A deep cut had damaged blood vessels and partially severed two tendons.
His life was not in immediate danger, but improper treatment could permanently damage his mobility.
It was not a simulated exercise.
The two young medical-nin were being evaluated using a real patient.
Tsunade and Shizune observed from behind a reinforced glass partition. Several senior medical-nin stood nearby, ready to intervene if either student made a dangerous mistake.
Ren looked at the patient's vital signs.
His heartbeat was elevated but stable. The anesthesia was working, and the bleeding had been temporarily controlled.
Ren held out his hand.
"Hemostatic forceps."
Rin immediately placed the instrument in his palm.
Ren exposed the injured area and began repairing the damaged blood vessel. His hands remained steady, even when fresh blood welled up around the wound.
"Two fragments are still lodged near the lower edge," he said. "Remove them with the tweezers. Don't pull upward. One of them is close to a nerve."
"Understood."
Rin inhaled slowly before lowering the tweezers.
Her first movement was slightly stiff.
Ren noticed but did not rush her.
"Follow the angle of entry," he instructed. "If the fragment went in diagonally, removing it vertically will cause more damage."
Rin adjusted her grip and carefully extracted the first shard.
A faint metallic sound echoed as she placed it in the tray.
The second fragment was deeper.
Rin used gauze to clear the blood, located its edge, and slowly withdrew it along the same path through which it had entered.
The moment it came free, blood began flowing from a damaged vessel.
Rin's eyes widened.
"Bleeding!"
"You expected that," Ren reminded her calmly. "Use the Healing Technique. Compress the vessel first, then seal the damage."
Rin forced herself to breathe.
Green medical chakra gathered around her fingers. She pressed down beside the wound, slowing the bleeding before carefully directing chakra into the damaged tissue.
The flow weakened.
"That's it," Ren said. "Maintain the pressure. I'm almost finished repairing the tendons."
Their coordination had been awkward at the beginning, but they gradually found a rhythm.
Ren sutured the damaged tendons while Rin controlled the bleeding and monitored the patient's condition. Whenever one of them required an instrument, the other had it ready before being asked.
Several tense minutes passed.
Ren tied the final surgical knot and inspected their work.
"Release pressure slowly."
Rin followed his instruction.
No new bleeding appeared.
The patient's heartbeat began to settle, and the numbers on the monitoring equipment gradually stabilized.
Ren and Rin looked at each other.
They had done it.
Together, they had completed a difficult surgical procedure without intervention from the supervising medical-nin.
Two system notifications appeared before Ren.
[Healing Technique favorability +1]
[Special Event—Personally Treat 100 Patients. Current progress: 23/100]
Ren suppressed his satisfaction until they had cleaned the surgical site, closed the wound, and ensured the patient could be safely transferred to recovery.
Only then did they leave the operating room.
They removed their gloves, masks, and surgical gowns before stepping into the corridor, where Tsunade and Shizune were waiting.
Tsunade crossed her arms.
"Hmph. Passable."
Rin's shoulders immediately stiffened.
"Your suturing technique was still too crude," Tsunade continued, looking at Ren. "The tendon alignment was acceptable, but you wasted several movements and placed unnecessary strain on your wrist."
Ren nodded.
"I'll correct it."
Her gaze shifted to Rin.
"Your response to the bleeding was too slow. If that had been a damaged artery instead of a smaller vessel, the patient's condition could have deteriorated before you recovered from your surprise."
Rin lowered her head.
"Yes, Lady Tsunade."
"However…" Tsunade deliberately paused, allowing the tension to build. "For two genin, your performance was adequate. The patient's condition is stable, and neither of you made an irreversible mistake."
She raised her chin slightly.
"You both passed. You may continue training with the Medical Corps."
Rin stared at her.
Then her entire face lit up.
"We passed!"
The weeks of pressure finally disappeared. Before thinking about what she was doing, Rin turned and wrapped both arms around Ren.
"That's wonderful, Ren! We actually passed!"
Her voice trembled with happiness and relief.
Ren stiffened in surprise, then smiled and gently patted her shoulder.
"You did well. You handled the second fragment better than you did during practice."
Rin suddenly seemed to remember where they were and who was watching. Her body froze before she quickly stepped back, her face turning bright red.
"I'm sorry! I was just excited."
"There's nothing to apologize for."
Shizune covered a small smile behind her hand.
Tsunade's expression became increasingly impatient.
"Enough celebrating in the middle of the corridor. Since you passed, go complete your reports before I change my mind."
Rin immediately straightened.
"Yes, Lady Tsunade!"
"Mik—" Tsunade stopped and corrected herself. "Ren, you stay. I need to speak with you privately."
Rin looked curiously between them but did not ask questions.
"I'll see you later, Ren."
She bowed to Tsunade and hurried down the corridor, still unable to hide her smile.
Once Rin disappeared around the corner, Tsunade's expression became serious.
"There's news about the Nerve Activation Technique you asked me to investigate."
Ren's attention sharpened.
Tsunade lowered her voice.
"I searched through Konoha's sealed medical archives. The village did conduct research into nerve activation several years ago, but the project was terminated and its records were restricted."
"Why was it terminated?"
"Because the risk was unacceptable."
Tsunade's eyes hardened.
"The researchers attempted to stimulate the nervous system using chakra, hoping to improve reaction speed, muscle response, and information transmission between the brain and body."
"In theory, the method was sound. In practice, the human nervous system could not tolerate the strain."
She paused before delivering the result.
"More than a dozen participating shinobi suffered permanent nerve damage. Several experienced seizures, paralysis, or organ failure. Others were left brain-dead."
Ren remained silent.
"Even among the few successful subjects, the improvement was far below expectations," Tsunade continued. "Some gained slightly faster reactions, but the effects were unstable and placed enormous stress on their bodies."
She stared directly into his eyes.
"Knowing that, do you still want to examine the research?"
"Yes."
Tsunade's brow furrowed.
Ren continued before she could refuse.
"I don't intend to reproduce the experiments or recklessly test the technique on myself. I want to understand how chakra was used to stimulate the nerves, why the process failed, and what dangers the researchers overlooked."
"You're planning to create a different technique."
"I'm considering the possibility," Ren admitted. "But I need to understand the failed approaches before attempting anything. Knowing what killed the previous subjects may be more valuable than studying the few successful cases."
Tsunade watched him for a long moment.
Finally, she exhaled.
"Fine. Follow me."
She turned and walked away.
Ren expected her to lead him toward her office or one of the hospital's archive rooms.
Instead, Tsunade left Konoha Hospital entirely.
They moved through the village for approximately ten minutes, heading toward a quiet district near the outskirts. The streets became less crowded, and ordinary residences gradually disappeared.
Eventually, they stopped before an unremarkable stone building.
From the outside, it resembled a small administrative facility. There was no sign identifying its purpose, and its windows were narrow enough to prevent anyone from seeing inside.
Ren immediately noticed the shinobi stationed around the building.
They wore ordinary Konoha uniforms, but their chakra signatures were carefully concealed. Several others watched from hidden positions on nearby rooftops.
A barrier surrounded the entire structure.
When Ren followed Tsunade through the entrance, a cold sensation passed across his skin. It felt as though he had stepped through the surface of invisible water.
The barrier had inspected him.
Had Tsunade not been beside him, the guards would likely have stopped him before he reached the door.
The interior was much larger than the exterior suggested. Corridors branched in several directions, and sealed doors marked with warning symbols lined the walls.
"This is the Konoha Research Institute," Tsunade explained. "Most of the village's official research into new ninjutsu is conducted here."
Ren looked toward a sealed staircase descending underground.
"Who manages it?"
Tsunade did not slow down.
"Orochimaru."
The name caused Ren's eyes to narrow.
"The Nerve Activation records are stored in this facility," Tsunade continued. "Because they're classified, you may only read them here. You're forbidden from removing the documents, copying them, or discussing their contents with anyone who lacks authorization."
She stopped outside a reinforced door and turned toward him.
"I vouched for you personally. You'll have three days of access, and every document you request will be recorded."
Tsunade's eyes became dangerously sharp.
"Do not make me regret trusting you."
Ren nodded.
"I understand."
Tsunade placed her palm against the seal on the door.
Lines of chakra spread across its surface, and a heavy locking mechanism began to turn somewhere inside the wall.
Beyond that door waited the remains of a project that had crippled shinobi, destroyed minds, and killed its own test subjects.
It also waited inside a research institute controlled by Orochimaru.
For the next three days, Ren would be searching for a way to sharpen his nerves inside the most dangerous laboratory in Konoha.