The next day, Orochimaru's laboratory.
The fusion rate with First Hokage cells had reached 50%.
Kakashi frowned as he reviewed the latest test results.
Due to the appearance of Yamato, Orochimaru had become obsessed with studying upgraded variants of Hashirama's cells—aiming to reduce the difficulty of acquiring Wood Style. As a result, all prior villager screening experiments had been halted.
The data Kakashi held came from tests using his own cells. A 50% compatibility rate was quite low. Even if he succeeded by sheer luck, he'd only barely be able to maintain equilibrium. If his body failed to suppress the cells, it would backfire just like it had on the previous test subjects.
Look at Danzo in the original timeline—he'd implanted an entire arm full of Sharingan to control the First Hokage's power. In the end, his body had become an unrecognizable mess. Disgusting, even.
Kakashi would never accept such a price.
Sadly, it was clear he couldn't enhance his potential simply by fusing First Hokage cells—at least not in the short term.
It was time to activate a backup plan.
With that, Kakashi informed Lord Orochimaru of his intentions. He left a Shadow Clone in the lab, using half of his chakra to ensure the clone could continue the research in his absence. Then he made his way to Tsunade's office.
"Tsunade-sister, are you in?"
He knocked on the door.
"It's Kakashi? Come in," Tsunade's lazy voice responded from the other side.
Kakashi entered and immediately noticed the faint red marks on her face and the water stains at the corners of her mouth. She hadn't even wiped off the drool.
Wow. Sleeping in the middle of the day? So this is the life of a dean? Looks like she's living pretty leisurely...
"Ahem... What brings you here at this hour?" Tsunade asked, trying to appear nonchalant as she subtly wiped her face.
"Sister Tsunade, I want to go to the Wet Bone Forest to learn Senjutsu."
Tsunade raised an eyebrow in surprise. "You want to learn Sage Mode? Do you know how dangerous it is? One misstep and you could die."
"I understand the risks," Kakashi replied seriously. "I'm mentally prepared."
Tsunade hesitated for a moment, but knowing Kakashi's talent, she decided not to dissuade him further.
"Alright. If it's you, it might actually work."
She led him downstairs to the courtyard and took out a scroll.
"This is the summoning contract for the Wet Bone Forest. Sign your name in blood, and let's see how big a Katsuyu clone you can summon. Remember, Katsuyu's clones are part of the Immortal herself, so be respectful."
Kakashi nodded solemnly. Channeling chakra into his left hand, he used a chakra scalpel to cut his right index finger and signed his name in blood: Hatake Kakashi.
As someone who already knew his family's Summoning Technique, the contract process went smoothly. As for distinguishing between different summons, it was simple: when summoning, you only needed to silently think of the specific creature in your heart. A spiritual bond would do the rest.
"Hai-Xu-You-Shen-Wei... Summoning!"
Bang!
With a puff of smoke, Kakashi suddenly felt himself lifted into the air. The hard ground beneath him had turned soft. Beneath him now stood a Katsuyu clone the size of a house.
He reached down and curiously touched its surface. It was soft and elastic—surprisingly pleasant. Its translucent, jelly-like skin gave it the appearance of a silicone toy.
Thankfully, it wasn't slimy or sticky like he had feared. In his past life watching anime, he always imagined Katsuyu to be a dripping, slippery slug. Reality, however, was far more tolerable.
"Lady Tsunade, is something wrong?" Katsuyu asked gently, scanning the area. Seeing no battle or wounded, she tilted her head in confusion.
Tsunade smiled approvingly—this clone's size was impressive for such a young summoner.
"I didn't summon you this time. Meet Kakashi, my disciple—and your new contractor."
"Oh, I see. It's nice to meet you, Master Kakashi. Please take care of me."
Katsuyu's tentacles waved respectfully.
"Please don't call me 'Master.' I haven't even graduated from the Ninja Academy!" Kakashi waved his hands in protest.
"It's a sign of respect toward one's contractor, Lord Kakashi," Katsuyu replied calmly.
"Alright, names aside," Tsunade said, cutting in. "Let's get down to business. Kakashi wants to train in Sage Mode. Please take us to the Wet Bone Forest."
Katsuyu nodded.
Bang!
Kakashi's vision blurred as he felt his body pulled into a swirling vortex. Moments later, the darkness receded, and light returned.
"Sister Tsunade, is this… Katsuyu Sage's residence?"
"Yes. Welcome to the Wet Bone Forest."
Tsunade pointed ahead.
A sea of towering green mountains stretched into the distance, layer upon layer. As the wind passed through, the forest rippled like waves—breathtakingly beautiful.
But upon closer inspection, something felt off.
The tops of the trees were lush and vibrant, stretching skyward. The lower halves, however, were pale, thin, and sickly—like they had been gnawed away. The contrast was eerie, like a forest made of bones.
On a giant tree nearby, a gargantuan Katsuyu was half-lounging while gnawing on the trunk. By Kakashi's estimation, this Katsuyu had to be at least 3,000 meters long.
"That's my real body," the clone beside Kakashi said. "This entire forest is my food supply."
So this was the true form of the Katsuyu Sage?
With that size, the natural energy stored in her body must be astronomical.
Or perhaps... as a true Sage, her form had already become one with nature itself.
Kakashi took a deep breath and re-centered himself. Despite being a forest, the Wet Bone Forest was strangely quiet. No birds, no insects. Nothing but silence.
"Little Tsunade, little Kakashi, welcome to my home," said a gentle voice.
"That's my main body you see. I'll communicate through this clone while I eat—it's my favorite pastime, after all. I hope you don't mind."
"Of course not, Sage Katsuyu," Kakashi replied respectfully, realizing the true Sage was now speaking.
Katsuyu nodded, satisfied. "Kakashi-chan, has Tsunade explained what Senjutsu really is?"
Kakashi shook his head.
"The essence of Senjutsu lies in balancing three energies—spiritual energy, physical energy, and natural energy. Only when they are in perfect harmony, in a 1:1:1 ratio, can one enter Sage Mode."
"In that state, Ninjutsu, Taijutsu, and Genjutsu are all drastically enhanced. And thanks to the Wet Bone Forest's unique methods, your regenerative ability will skyrocket as well."
Tsunade's eyes lit up. "Like my grandfather, Senju Hashirama?"
"Little Hashirama?" Katsuyu chuckled. "Yes, he learned Sage Mode here with me."
She paused, reminiscing. "He was special—not just capable of Sage Mode, but born with a body close to that of an immortal. He mastered the technique perfectly in just one day. That kind of talent is exceedingly rare."
Tsunade remained silent, remembering Hashirama's overwhelming power. Even with Kakashi's brilliance, she doubted he could match a god-like figure.
Still... Kakashi never lost in terms of learning speed.
"Little Kakashi, I'll now demonstrate how to sense and absorb natural energy. Watch carefully. Do not let your mind wander!"
Katsuyu's tone grew firm.
"Natural energy is violent. If you fail to control it, your body will begin to mutate—and eventually, you'll become part of me."
"Wait... are you saying all previous trainees...?"
"Indeed. Except for little Hashirama, every other practitioner has become one with my body."
What the hell?!
No wonder there weren't any statues here, like the stone ones at Mount Myōboku.
So let's review:
Fail at Mount Myōboku? Turn to stone.
Fail at Ryūchi Cave? Eaten by the White Snake Sage.
Fail here? You become part of Katsuyu's body?!
Kakashi shuddered at the image of himself turning into a slug.
"So, Kakashi," Katsuyu said gently, "if you'd like to change your mind, there's still time."
After all, she cherished her contractors—they were her only connection to the outside world.
Kakashi's eyes shone with determination. "No need. I'll master it."
Seeing his resolve, Katsuyu didn't press further. Instead, she broke down the Sage Mode process step by step, using her body's instinctive control as a model.
"Now, focus. I'll assist you in absorbing the energy. If anything goes wrong, I'll stop you immediately. Now—"
"Eh? EHH?!"
Katsuyu Sage suddenly reared back in shock, her tentacles twitching in disbelief.
Tsunade, meanwhile, wore a familiar expression—I knew it.
Kakashi now stood calmly before them, his eyes open, with distinct black Madara-like lines etched around them—he had already entered Sage Mode.
He scratched his head sheepishly. "Umm... I think I got it, Master Katsuyu."
Tsunade had the sudden urge to punch him. Hard.
"Ah... amazing. Kakashi-chan, you've already graduated," Katsuyu Sage said, still in disbelief.
In all her long life, only two people had managed to surprise her like this.
"Even young Hashirama needed a full day to master Sage Mode. But you... you did it instantly. This kind of talent may only compare to the Sage of Six Paths."
The Sage of Six Paths?
Though his power came from the Ōtsutsuki bloodline, Kakashi didn't believe blood alone determined greatness. He was born in Daxia, a land where nobles were forged—not born.
With Orochimaru's genetic research, plus his own copy system, Kakashi believed he could reach the same heights—one day.
His path was clear.
"Alright, now that you've learned Sage Mode, let's head back," Tsunade said.
"Leave it to me," Katsuyu replied, waving her tentacles as she cast the reverse summoning.
Bang!
With a flash of light, the two returned to Konoha.