His unwavering resolve filled Tanjiro and the others with awe.
Rin, however, simply shook his head.
"If you're dead, who's left to enjoy the outcome? That's a terrible bargain."
"You all rest. I have something to take care of."
Ignoring their complicated expressions, Rin turned and walked down the corridor, returning to his room and sliding the door shut behind him.
Sitting cross-legged on the tatami, Rin closed his eyes and summoned the system interface in his mind.
[Current Dimension Points: 23,990]
His current template was Uchiha Sasuke at the Eternal Mangekyo Sharingan stage.
The power of the Sharingan originated from Indra Ōtsutsuki, the eldest son of the Sage of Six Paths. At its core, it was the extreme application of Yin Release.
Yin Release represented spiritual energy, capable of giving form to the intangible. Techniques like Amaterasu's black flames and Susanoo's defense were both manifestations of Yin Release.
However, this system prioritized offense over recovery.
If he were to suffer a fatal injury, or attempt to interfere with the boundary between life and death, relying solely on Yin Release and conventional medical ninjutsu would not be enough.
To truly eliminate that weakness—or even gain the ability to alter lifespans and restore life—he needed to complete the other half.
"System, check the cost to exchange for Yang Release."
[Ding! Searching for target ability…]
[Yang Release: One of the secret techniques derived from the Sage of Six Paths. It represents physical energy and can imbue life into form. Those who master Yang Release possess immense vitality and near rule-level healing abilities, such as regenerating severed limbs and saving those on the brink of death.]
[Exchange Requirement: 20,000 Dimension Points]
"Twenty thousand… within range."
Rin didn't hesitate.
"Confirm exchange."
[20,000 Dimension Points deducted. Beginning integration of Yang Release…]
A low hum echoed as the system notification faded.
An entirely different kind of energy descended into Rin's body.
If Yin Release was a cold, endless abyss, then the Yang Release now flowing through his limbs was like a warm, vibrant sun.
There was no tearing pain—only an indescribable sense of comfort.
Rin could clearly feel every cell in his body absorbing the immense life force.
The cold, sharp edge in his mind—shaped by prolonged use of the Sharingan—began to soften, gradually reaching a balanced state under the influence of this warmth.
Yin and Yang converged.
Though it was far from the godlike Six Paths Yang Power seen in the later stages of Naruto, simply mastering Yang Release was already a miracle in this world.
Rin opened his eyes. A soft glimmer flickered within his pitch-black pupils.
He raised his right hand, focusing his thoughts. A pale green light gathered in his palm, radiating gentle vitality. In the gap between the tatami, a tiny seed stirred, breaking through the surface. Within seconds, it grew into a fresh, tender blade of grass.
"This is the power of life."
Rin closed his fist. The green glow faded, and the grass stopped growing.
He pushed the door open and walked toward the backyard.
At that moment, Rengoku Kyojuro sat by the corridor while Kocho Shinobu conducted a routine post-battle examination.
Holding a stethoscope, Shinobu's brows gradually knit tighter.
"Rengoku-san, your cardiopulmonary function just underwent a dangerously high level of strain."
She set the stethoscope aside, her expression serious.
"There may be no visible injuries, but your cellular activity has been severely overdrawn. If what Rin-san said about the Demon Slayer Mark is true, your current condition has already cost you at least a year of your lifespan."
"Umu! That is already an excellent outcome! Please, do not worry about me!"
Rengoku's voice rang out as usual, full of energy.
"As a doctor, how could I not worry?" Shinobu bit her lip. The casualty rate among the Hashira was already alarmingly high, and now there was a power that consumed one's lifespan. The thought of the coming battle left her feeling helpless.
"Don't look so gloomy. You'll get wrinkles."
Rin's voice sounded from behind them.
He walked over, casually ruffling Shinobu's hair before sitting down beside Rengoku.
"Rin-san… do you have a way to deal with this?"
Shinobu asked immediately, not even bothering to brush his hand away. She knew better than anyone that he was capable of miracles.
"Give me your hand."
Rin looked at Rengoku.
Without hesitation, Rengoku extended his arm.
Rin placed two fingers lightly on his wrist.
In the next instant, pure Yang Release chakra flowed from his fingertips into Rengoku's body.
The moment that pale green light touched his skin, it felt like spring rain nourishing parched earth.
Rengoku felt a warm current spread through his body. His organs, which had been strained by forcibly activating the Demon Slayer Mark, began to absorb that energy greedily, as if finally receiving long-needed sustenance.
The depleted cellular activity recovered at a rate visible to the naked eye.
In just ten seconds, Rin withdrew his fingers.
"Check again."
He gestured to Kocho Shinobu, who was still staring in a daze.
Shinobu picked up the stethoscope again, half in disbelief. But the moment she listened to Rengoku's heartbeat and pulse, her violet eyes widened in shock.
"This… how is this possible?"
She murmured under her breath.
"The lost vitality has been restored… not just that, even old, hidden injuries have healed. This completely defies medical logic!"
"Umu! I feel as light as if I could take flight! Even my breathing is a hundred times smoother!"
Rengoku waved his arm, his face full of surprise.
Rin stood up and brushed off his sleeves.
With the Yang Release, the lifespan drawback of the Demon Slayer Mark was no longer an issue for him.
As long as a person wasn't completely dead, he could forcibly restore their vitality.
"The so-called price only exists because you lack the means to replenish life force."
Rin glanced at Shinobu, a faint smile tugging at his lips.
"Since this works so well, get ready. We're heading to the Ubuyashiki Estate tomorrow."
Shinobu was momentarily stunned.
"To headquarters? Oyakata-sama hasn't summoned us."
"To treat an illness."
Rin slipped his hands into his pockets, his gaze drifting into the distance.
"That master you revere so much walks around every day with a body eaten away by a curse, coughing like a broken bellows. It's unpleasant to watch."
If he wanted the Demon Slayer Corps to serve as his eyes and ears in tracking Muzan, he might as well remove the Ubuyashiki family's short-lived bloodline curse while he was at it.
[Dimensional Template System]
[Host]: Rin
[Current Template]: Uchiha Sasuke (Eternal Mangekyo Sharingan Era)
[Template Compatibility]: 100%
[Innate Abilities]
Ninjutsu: Yin-Yang Release (initially formed), Lightning Release, Fire Release, Yin Release, Yang Release, Basic Three Body Techniques
Dojutsu: Eternal Mangekyo Sharingan (no side effects; includes heightened perception, genjutsu immunity, Amaterasu, Blaze Release: Kagutsuchi, Perfect Susanoo)
Taijutsu: Uchiha Style Kenjutsu, Sharingan-assisted combat
[Equipment]: Kusanagi Sword (modified), wisteria sachet
[Dimension Points]: 3,990 (23,990 accumulated − 20,000 spent on Yang Release)
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