Feeling the burning sensation in her abdomen, Tsunade's expression immediately changed.
It hadn't been long since she escaped from Hikari's Tsukuyomi illusion, and this sensation instantly reminded her of certain experiences within the dream.
To reiterate, Tsunade hadn't encountered any truly "adult" situations in the Tsukuyomi.
So why was she having this physiological reaction now?
Why did she feel that if she had escaped even a moment later, it would have been too late?
There's a psychological experiment called "Pavlov's Dog."
Every time before feeding the dog, a bell would ring.
Over time, even without food, the dog would start salivating uncontrollably whenever the bell rang.
For example, when a certain country had a rampant bear problem, clever "experts" suggested having students wear bells on their backpacks, believing the ringing would scare away bears.
Instead of scaring the bears away, the bells made the bears think it was a dinner bell, causing them to hunt the students.
This phenomenon is a conditioned reflex—an automatic response that doesn't require conscious thought.
Even intelligent beings like humans find it difficult to resist when faced with it.
Essentially, it's about linking two seemingly unrelated things in the brain.
And Tsunade experienced this association in the illusion.
She became Pavlov's dog.
The most terrifying part was that these two things weren't actually unrelated.
Even though Tsunade, as a Medical Ninja, didn't have deep expertise in psychology, she managed to understand the problem through related medical knowledge.
That's why Tsunade felt a sense of belated fear—she had nearly developed a conditioned reflex that could be described as "thinking of you makes me go ohohohohoho."
And now, feeling the burning heat in her abdomen, Tsunade immediately remembered it again.
Her body reacted before her brain could stop it.
However...
"Hmm?"
Tsunade touched the bath towel belt tied around her waist and found that the stone had disappeared.
She pulled open the belt, and sure enough, the stone hadn't fallen out.
Had it merged with her body?
Before Tsunade could ponder further, an even more intense sensation began to spread.
After activating the Strength of a Hundred Seal, her body became covered with black tattoo-like patterns that appeared due to the chakra surge after releasing the Yin Seal.
These black patterns were essentially chakra transport highways, designed to quickly and safely circulate the massive chakra stored in the forehead seal throughout her entire body.
Now, the black patterns on Tsunade's body—starting from her abdomen and spreading outward—began to steadily turn golden.
The Natural Energy contained in the stone Makoto had given her seemed to be fighting for territory, vying for control with the chakra stored in Tsunade's Yin Seal.
As the gold color drew closer to her head where the Yin Seal was located, the spread of the patterns gradually slowed down.
Meanwhile, her arms, which were farther away, had already been completely covered in glowing gold lines.
During this process, Tsunade's body was continuously being torn apart by the violent energy and then reassembled through Creation Rebirth—an excruciatingly painful cycle of destruction and regeneration.
True to her reputation as one of the Legendary Sannin who had survived countless battles, Tsunade didn't utter a single sound.
She gritted her teeth and took it.
Watching the black patterns on Tsunade's body gradually being replaced by golden light, Makoto felt as if he were witnessing Illidan Stormrage being forcefully infused with Holy Light by the Naaru in World of Warcraft.
It seemed like Tsunade might shout "My destiny is my own!" at any moment and then eye-beam him!
But nothing of the sort happened.
Before Makoto's arrival, the ninja world had no one like Illidan—a chosen one who rejected the role of savior.
Everyone here was a slave to "Destiny" and "Prophecy."
Even in the Boruto era, the clone Kashin Koji was still dancing to fate's tune.
"Huh? Ah! Lady Tsunade, are you alright?!"
Shizune, who had been closely monitoring Tsunade's vitals, suddenly noticed the abnormality in her body and cried out anxiously.
Her gaze shifted to Makoto, pleading silently to stop the experiment.
"I-I'm fine."
Tsunade continued to endure stubbornly.
She looked down at her hand and understood why Shizune had cried out.
The skin on her hand had suddenly become wrinkled and shriveled—a clear sign of rapid aging.
Strangely, Tsunade didn't feel any loss of strength.
The pain hadn't subsided, and her body remained in peak physical condition despite the cosmetic decay.
Tsunade knew clearly that if she exhausted the chakra in her Yin Seal, the youthful appearance she maintained with it would disappear.
So why was this happening now?
Was it because the chakra in her Yin Seal was being consumed by the Natural Energy spreading from Makoto's stone?
While pondering the reason, Tsunade had already found a corner, turned her back to Makoto, and crouched down with her head lowered.
Clearly, Tsunade didn't want anyone—especially Makoto—to see her aged appearance.
For now, only her limbs had begun to age, but it was likely that her body and face would change soon.
It was understandable.
Even the author, Kishimoto, rarely let the audience see Tsunade's true aged form.
Makoto, however, had no particular morbid curiosity about it.
Instead, Tsunade's current situation made Makoto think of another question.
"Tsunade, have you ever looked in a mirror to see what you'd actually look like when you're old?" Makoto asked calmly.
"...No. Why?"
After a moment of silence, Tsunade, still crouching in the corner like a mushroom, answered Makoto's question.
In fact, not only had Tsunade never seen her aged self, but she had never reverted back since deciding to use the Yin Seal to maintain her youth.
In the original story, Tsunade aged twice: once during Pain's invasion, and once during the battle against Madara Uchiha.
Both times were because she exhausted her chakra healing others.
Without depleting her chakra, maintaining her youthful appearance was essentially a passive skill for Tsunade.
She explicitly stated that her youthfulness was from the inside out, not merely a superficial Genjutsu layer.
This means her physical condition was also at its peak, just like in her twenties.
Under these circumstances, it's hard to imagine why Tsunade would ever willingly revert to her older self.
However, this leads to a logical inconsistency.
During Pain's invasion, it was somewhat acceptable—after exhausting her strength, the aged half of her face looked about the same age as Jiraiya.
A normal 50+ year-old.
But in the battle against Madara? The aged appearance was truly terrifying.
It's important to remember that Tsunade's actual age is only fifty-something.
What does being fifty look like in this world? Hashirama and Tobirama died around that age.
Jiraiya was that age.
Now, look at the aged Tsunade after the Madara fight.
Are we sure that is what fifty looks like? She looked even older than Hiruzen Sarutobi, who was pushing seventy when he died!
If we had to find a comparable level of aging, only Onoki from the Boruto era—at ninety years old—showed a similar degree of decay.
The chakra from the Yin Seal is supposed to rejuvenate the body.
Logically, even if the chakra is depleted, she should at most revert to her original biological age.
How could she become even older than her actual years?
This phenomenon reminded Makoto of another similar character from fiction.