Uchiha’s grimoire guide to winning: chapter 10: Red eyes of Doom and neurochemistry

I had to literally read psychology papers for this chapter. I really hope y’all like it.

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"Of course, there were no instructions in the texts like what's the point? I had gone to speak with one of the elders and apparently, I was too young and not mature enough to know the requirements. Do you believe that? Me? Not mature enough."

I looked at her with a deadpan expression. "Totally."

She reacted as if she had been stabbed, clutching her chest dramatically.

But beneath the humor, my mind was already working through the implications. Due to the memories I had from my past life, from the manga, I knew that the Amaterasu was one of the abilities it was possible to gain through the unlocking of the Mangekyō Sharingan.

If I remembered well, both Sasuke and Itachi were able to use it, even if Sasuke could do so better due to his additional technique that allowed him to manipulate the flames once they'd been summoned. Itachi could only invoke them, could only place them where his gaze fell, but Sasuke, Sasuke could shape them, mold them, turn them into weapons and shields and constructs.

Like I'd thought earlier, unlocking the Mangekyō Sharingan came with abilities mostly tailored to their users, unique expressions of their psyche and circumstances. Unlike what most may think, all Uchihas by unlocking the Mangekyō didn't get Amaterasu and Tsukuyomi. Obito wasn't the exception to the rule with his Kamui and his intangibility. He was actually proof of how diverse the Mangekyō's abilities could be.

The only ability that could be said to be common amongst all users of the Mangekyō was the Susanoo, which needed the use of both Mangekyō eyes to manifest. Well, unless you were Madara and thus able to spew bullshit left and right, using Susanoo with no eyes at all during the war because apparently the rules didn't apply to reincarnations of Indra when the plot demanded it.

I knew why the elder had told my aunt that she was not mature enough. The Blaze Release, which in other words was the ability to shape, control, manipulate, do more than just invoke the dark flames of Amaterasu, was one of the abilities possible to gain by unlocking the Mangekyō. It was one of the two abilities, with the other being the basic Amaterasu invocation, that Sasuke had gained through his Mangekyō.

With the way my aunt was passionate about fire nature, obsessed even, I was certain that if she unlocked the Mangekyō, she would have access to an ability related to fire. The specifics would depend on her exact mental state and circumstances at the time of awakening, but given her entire fighting style and philosophy revolved around flames, it was almost guaranteed.

But then presented itself the problem, the reason why I knew the instructions had not been written down, why the elder had not shared them with her.

According to what most Uchihas in the know understood when it came to unlocking the Mangekyō, the solution to do so was to kill someone you held dear, someone you loved, whether it was a family member or your best friend. That was the legend, the dark secret passed down through whispers and warnings. That was why Itachi had supposedly killed Shisui, why the technique was considered cursed, why those who possessed it were often viewed with a mixture of awe and horror.

In those circumstances, I understood why the secret to possibly gain the Blaze Release was not shared with my aunt. What responsible elder would tell an eager, passionate young woman that the path to her dream required murdering someone she loved? That was a recipe for disaster, for corruption, for the kind of tragedy that had plagued the Uchiha clan throughout its history.

I knew my aunt, so I knew that even if she knew the "traditional" method, she would not in any case try to murder or kill somebody she loved. But she was my aunt and I had memories of literally growing up with her always at my side, so what I thought was probably different from what the elder thought. They saw an ambitious Jonin who might be tempted by power. I saw the woman who'd ruffled my hair and snuck me sweets and made me laugh even when I was drowning in memories of two different lifetimes.

It was also much a shame that everyone who thought that the Mangekyō could only be unlocked through personally caused tragedy were wrong, and that I was maybe the only one of my clan who knew this.

Tobirama Senju, the Second Hokage and probably the greatest scientific mind the shinobi world had ever produced when it came to understanding the mechanics of jutsu and kekkei genkai, had explained it during the Fourth Shinobi World War. I could remember his words almost perfectly, preserved by my past-life memories and the Sharingan's perfect recall working in concert.

The Sharingan, he'd explained, was connected to the brain in a very literal, physical way. Specifically, it responded to a special chakra that was produced in the brain. This chakra was released in response to strong emotions, particularly negative ones. When an Uchiha experienced profound loss, grief, or hatred, their brain released this special chakra, which then flowed through the optical nerves and into the eyes, catalyzing changes in the Sharingan.

The more powerful the emotion, the more of this special chakra was released, and the more dramatic the evolution of the Sharingan. A mild trauma might awaken dormant eyes or add a tomoe. A profound loss could fully mature the Sharingan to three tomoe. And the most intense emotional upheaval, the kind that fundamentally altered a person's entire worldview and psyche, could trigger the awakening of the Mangekyō Sharingan.

But here was the thing that everyone seemed to miss, the critical detail that Tobirama had mentioned but that most people glossed over because they were too focused on the "kill someone you love" narrative.

It wasn't the act of killing that mattered. It was the emotional impact.

I thought that this phenomenon could be seen in another way, a more scientific way that aligned with what I knew from both worlds.

In my opinion, what triggered the release of the Sharingan wasn't necessarily grief or hatred specifically, but any emotion sufficiently strong enough to literally impact the brain chemistry in dramatic ways.

Consider serotonin first. This was the neurotransmitter primarily responsible for mood regulation, emotional stability, and feelings of well-being. Under normal circumstances, serotonin maintained a relatively steady baseline, keeping emotions within manageable ranges. But during intense experiences, serotonin levels could fluctuate wildly.

Trauma, particularly the kind involving loss or betrayal, caused serotonin to crash. And I don't mean a gentle decline. I meant precipitous drops of fifty, sixty, even seventy percent below baseline. This was why depression and emotional instability were so closely linked to traumatic experiences. The serotonergic system had been fundamentally disrupted, leaving the person unable to regulate their emotional state properly.

But here was what most people missed: serotonin didn't just crash in response to negative experiences. It could also spike dramatically during moments of profound positive emotion. Feelings of deep contentment, perfect harmony, transcendent peace, those were all driven by serotonergic surges that could reach levels two or even three times above normal.

The key wasn't whether serotonin went up or down. The key was the magnitude of the change. A sudden, dramatic shift in either direction represented a fundamental alteration in brain chemistry, the kind of change that could ripple through every neural system in the body. For an Uchiha, whose eyes were already modified to respond to brain-generated chakra, that kind of neurochemical earthquake could easily trigger the release of the special chakra Tobirama had described.

Then there was oxytocin, and this one was particularly fascinating when you considered the Mangekyō's supposed unlock conditions.

Oxytocin was commonly called the "love hormone" or "bonding hormone." It flooded the system during moments of social connection, trust, and attachment. When you hugged someone you cared about, when you felt that warm sense of belonging, when you looked at someone and felt completely safe and understood, that was oxytocin at work.

But here was the thing most people didn't realize, the critical detail that reframed everything: oxytocin levels also spiked in response to the loss of social bonds.

When someone you loved died, when a relationship shattered, when you were suddenly and violently separated from someone you'd felt deeply connected to, your brain released massive amounts of oxytocin. It was as if your mind was desperately trying to maintain an attachment that no longer existed, flooding your system with the same hormone that had reinforced the bond when the person was still there.

This might explain why losing someone you loved was so devastatingly effective at triggering the Mangekyō. It wasn't just the grief, the pain, the sense of loss. It was that your brain was simultaneously processing the absence while flooding your system with the hormone associated with presence and connection. You were experiencing maximum attachment and maximum separation at the same time.

That kind of profound contradiction, that simultaneous firing of completely opposed neural patterns, created a neurochemical crisis that the brain struggled to resolve. The oxytocin was screaming "bond is present and strong" while every other sensory input was screaming "bond is gone forever." That cognitive dissonance, that impossible-to-reconcile contradiction between what your hormones were telling you and what reality was showing you, could easily generate the kind of extreme chakra release necessary for Mangekyō awakening.

But, and this was the critical insight that everyone seemed to miss, oxytocin also spiked during moments of intense positive bonding. The birth of a child produced oxytocin surges that could rival or exceed those associated with loss. A moment of perfect understanding with someone you loved, a profound sense of being truly seen and accepted, a transcendent experience of connection, these could all create oxytocin levels that went far beyond normal ranges.

The difference was in the context, not the magnitude. Loss combined with oxytocin created unbearable contradiction. But profound connection combined with oxytocin created perfect harmony, a sense of completeness so intense it was almost painful in its beauty.

Both could theoretically trigger Sharingan evolution. Both represented massive departures from normal neurochemical baselines. Both fundamentally altered brain state in ways that could generate that special chakra.

The serotonin and oxytocin systems also interacted in complex ways. Serotonin influenced oxytocin release, and vice versa. A crash in serotonin could amplify the contradictory nature of an oxytocin spike during loss, making the cognitive dissonance even more severe. Conversely, a surge in serotonin could enhance an oxytocin spike during bonding, creating a state of neurochemical euphoria that might be intense enough to trigger evolution.

What I was proposing was simple: the Sharingan responded to neurochemical extremes, not to specific emotions. Grief worked because it reliably created those extremes through serotonin crashes and paradoxical oxytocin spikes. But other experiences could create equally dramatic changes through different combinations.

Intense joy combined with profound bonding could spike both serotonin and oxytocin simultaneously to extreme levels. Perfect understanding or acceptance could create a sense of harmony so complete that it fundamentally rewrote neural patterns. Even something like the experience of unconditional love, given and received in perfect balance, could generate the kind of neurochemical transformation necessary for Mangekyō awakening.

The tragedy-focused narrative persisted because it was reliable. Killing someone you loved practically guaranteed the neurochemical upheaval necessary. But reliability didn't mean exclusivity. It just meant that this world was cruel and fucked enough that this seemingly became the only option.

Still, while my theory meant that trauma was not necessary in unlocking further stages of the Sharingan, it still didn't change the fact that finding something, making an event that would significantly affect the brain chemistry of my aunt to the degree necessary for Mangekyō awakening was something that sounded more complicated than worth it in my opinion.

How do you deliberately trigger a neurochemical cascade intense enough to catalyze Mangekyō awakening without resorting to trauma? How do you create joy so profound, understanding so complete, love so overwhelming that it literally rewrites brain structure? Those weren't things you could schedule or plan well unless I wanted to become ninja Walter White.

And all of that didn't include the fact that the Mangekyō progressively, the more it was used, caused blindness in its user unless they were able to switch Mangekyōs with a close relative who also had their own Mangekyō, creating what was called the Eternal Mangekyō Sharingan.

The only ones in the manga who didn't have to fear the blindness of the Mangekyō had been Obito, due to the Hashirama cells he had been implanted with that somehow arrested or reversed the degeneration, and Indra who, if I remembered well, was born either with an Eternal Mangekyō or a lesser version of the Rinnegan in the manga at least, because the anime had completely messed up that part with inconsistent flashbacks.

Wait. Indra hadn't needed to unlock the Mangekyō or to switch eyes with anyone. He'd been born with advanced eyes, had progressed to even more powerful states without any of the normal requirements or drawbacks. He was Indra Ōtsutsuki, son of the Sage of Six Paths, possessing a significant fraction of alien genetics that normal Uchiha had diluted over generations.

I might have an idea.

I looked at my aunt. "Auntie, are we alone?"

The expression on her face morphed to utter seriousness in such a way that I would have thought my laughing aunt from moments ago an illusion. The transformation was instant and complete. Her posture straightened, her eyes sharpened, her entire demeanor shifting from playful family member to experienced Jonin evaluating potential threats.

She closed her eyes for three seconds, and I felt rather than saw the pulse of chakra as she performed some kind of sensory technique. When she opened them again, she spoke with certainty. "We are alone. It's about your abilities, isn't it?"

My mind was racing with the implications of what I was about to propose. The pink slime, according to what I understood, was supposed to make someone the queen version of their species. The superior version. The apex.

For an Uchiha, that probably meant one of two things. Either it would push them toward becoming an Ōtsutsuki, since that alien clan were the ancestors of the Uchiha bloodline, the source of the Sharingan itself through Kaguya and her sons. Or it would create something like Indra, who as the son of Hagoromo and grandson of Kaguya, was a quarter Ōtsutsuki, a quarter alien, carrying enough of that extraterrestrial genetic material to transcend normal human limitations.

In either case, it probably meant not only unlocking all the stages of the Sharingan and beyond, but also being untouched by the inconveniences that plagued normal users. The progressive blindness of the Mangekyō. The chakra drain. The physical deterioration. Indra hadn't suffered from any of that. The Ōtsutsuki clan certainly didn't. They used their dōjutsu freely, without fear of losing their sight or burning out their life force.

If the pink slime could elevate my aunt to that level, could give her the genetic advantages that Indra had possessed by birth, then she could have her Mangekyō, could use it freely, could master the Blaze Release she dreamed of, all without the curse of blindness hanging over her head like a executioner's blade.

The question was whether my theory was correct, and whether I could actually use the ability safely. But that was what testing was for.

I took a breath. "I know how you could reach the next stage of fire manipulation, Auntie."

Her eyes widened in shock. "How?!"

Then her eyes narrowed, her analytical mind already working through possibilities. She thought out loud, "Your abilities, of course."

I neither denied nor agreed. Better she thought such. I was not going to tell her that it was because I had lived a previous life in which this universe was a manga.

"I can't promise you anything," I continued carefully, "but one of the abilities I discovered I had gained after the clan meeting is one that, more than just healing, should be able to get you to reach the next stage through another way that is both simpler and safer than the normal one."

She looked at me for a long moment, her Sharingan briefly flickering to life as if trying to read truth in my expression. Then, slowly, a small smile bloomed on her face. She leaned down and kissed me on the forehead, the gesture so gentle and fond that it made my chest ache. "You're such a sweet child, Ren. You don't have to, you know?"

"Huh?"

"Try to handle my grown-up problems," Fumiko said softly. "I know the clan head said a lot of things about how your abilities will help all of us, all of the clan, but don't forget, never forget, they are yours first. You're not an object, a tool, little Renny, no matter what they or yourself may try to believe."

"I know that," I said softly. "I am doing this just because I want to. Is wanting to help you wrong?"

"Of course it's not wrong, you're not wrong, Ren," she said quickly. "It's just, thinking about it, it's like a dream coming true, but at the same time, it feels like using my itty little nephew and I know it's not necessarily logical but us Uchihas have never truly been that logical. I am thankful, I am happy, but... I don't know."

She ruffled her own hair with one hand and sighed. "I am not good with things like this."

I let a teasing tone enter my voice. "Clearly. Could have just said thank you, my so incredible and cool and favorite nephew."

She smiled, the tension breaking. "You're right." Then, with exaggerated formality, "Thank you, my so incredible and cool and favorite nephew."

Her expression turned more serious again. "We'll wait for your mom, your dad, and the two others and try to firstly understand the ability, ensure that it's not harmful to you before anything."

I left her lap, standing up and stretching. My body still ached from the training, but it was a good ache, the kind that came from pushing limits rather than injury.

Fumiko stood up as well, brushing grass from her Jonin uniform. "It's time to go. We passed more time here than I thought we would."

She helped me to my feet by grabbing my arm, her grip careful but firm, and we began walking away in the direction of the clan compound. The sun was lowering on the horizon, painting everything in shades of orange and gold.

We walked in comfortable silence for a few minutes, just the sound of our footsteps and the evening insects beginning their songs. Then Fumiko spoke again.

"Hey, Renny, I had told you that I believed you would become someone as strong as Madara and Hashirama. I was wrong."

She turned to look at me, and the fading sunlight caught her just right. The dusk rays fell around her, illuminating her dark hair until it seemed to glow with an inner fire. Her face was cast in warm light that softened her features, made her look younger, more peaceful. The orange-gold luminescence created a halo effect, tiny particles of pollen or dust catching the light like floating embers around her head. Her eyes, dark and warm without the Sharingan active, held an expression of such genuine affection and pride that it made something in my chest constrict.

She looked ethereal in that moment, like something out of a painting, a figure of light and warmth against the darkening sky.

"You'll be stronger," she said, her smile growing, "because you're kind."

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Failed roll:

Messenger Cards [200 - Sailor Moon] These are blank cards that imprint vague images on themselves when you hold them and picture the image in your mind. You may plant these cards in places where the recipient can find them, and they won’t question how the card got there. The intended recipient of these cards will always recognize the images on these cards and will know exactly what it means, so if one wishes to give someone a sign to act, or to warn them of someone, they may use these cards

200 cp banked