"Ugh-"
Thump!
Karin and Konohamaru looked somewhat helplessly at the two people beside them.
One man, possessing arguably the strongest physical body on the sea, got 'seasick' from the slightest bump.
The other, immensely powerful, with the dual detection hacks of Observation Haki and Sharingan, kept tripping over flat ground.
Karin covered her forehead.
She knew the cost of the previous battle against Kaguya might be high, but she hadn't imagined it would be this high!
As for Konohamaru, he was completely out of the loop.
It had been a few hours since the sky battle when Karin finally brought him back from the Groseade.
From her, he roughly understood what Naruto and Sasuke had done.
"Naruto Aniki, are you okay? Here, have some water."
Konohamaru had to stand on his tiptoes to barely pat Naruto's back, then fetched some fresh water from the cabin.
"Thanks, Konohamaru… ugh... I'm fine... I'll be okay in a bit..."
To be honest, even Naruto himself hadn't expected that combining with this world's Natural Energy would produce such severe side effects.
-Actually, calling them side effects isn't entirely accurate.
While there are no other cases for comparison, if a Ninja who had learned Sage Mode came to the One Piece World and combined with the Natural Energy here, they would likely only develop some 'affinity for water'.
It would manifest as wanting to swim in the sea, craving seawater, feeling uncomfortable on land, or, in severe cases, growing a few fish scales or gill-like organs.
Well... somewhat similar to Fish-Men.
Looking at it this way, perhaps there's a reason why Fish-Men in this world are naturally physically stronger than humans.
However, the problem was that Naruto was a Devil Fruit user.
As everyone knows, Devil Fruit users are beings 'rejected' by the sea. The actual reason is a certain factor found in various materials… especially most abundant in seawater.
Pyrobroin.
It can be understood as 'the sea's crystallization'. It exists not only in ordinary seawater but even in Skypiea's cloud islands and special minerals.
[Seastone] is one example.
So, if this special substance exists in so many sea-related things, might it also exist within the Natural Energy here?
Naruto proved it through personal experience.
It exists.
Not only does it exist, but its concentration is surprisingly high.
Frankly, after entering the [Ocean Sage Mode] state, Naruto felt an extreme sense of discomfort, almost making him want to interrupt the process.
He had originally wanted to use Natural Energy to amplify himself, to see if he could kill Kaguya in one go.
Unexpectedly, he accidentally created that special water stream that washed Kaguya away into nothingness.
It wasn't that he didn't want to finish Kaguya himself. Mainly, at that time, Naruto's body had fallen into a state of 'exhaustion', perhaps unable to take even one more step.
But at the same time, this wasn't without benefits.
At the very least, Naruto felt that in that state, his attacks would deal significantly higher damage to all Devil Fruit users and their created subordinates.
For example, Imu, or Kaguya, whose body was created using Imu's power.
Before that seemingly gentle water stream, actually a high-concentration Pyrobroin energy impact, they had almost no resistance. Their bodies melted away in the blink of an eye.
Having lost Imu's power, Kaguya herself was just a remnant consciousness. After leaving Naruto's body, she had no possibility of existing anymore.
The Kama mark on his hand had disappeared after the other gained a physical body. Fortunately, the Otsutsuki genes Naruto obtained through the Baku Baku no Mi were still present.
After all, unlike Karin's case of temporarily using Otsutsuki power through the Kama, his situation was more like developing a unique Otsutsuki physique belonging to the Uzumaki Clan.
This special Sage Mode was indeed a 'special attack' against Devil Fruit users.
The drawback was that none of them, being Devil Fruit users themselves, were suited to use this technique.
"Hmm?"
Just thinking of this, Naruto turned his gaze to Konohamaru, who had been looking at him with concerned eyes.
'Oh my... what a coincidence.'
"?"
Konohamaru was taken aback by the stare.
"Naruto Aniki, why are you looking at me like that?"
The response was Naruto's hand on his shoulder.
"Konohamaru... ugh... Would you like... to learn Sage Mode?"
Upon hearing this, Konohamaru's eyes instantly lit up.
"That ability that directly defeated that Kaguya person?! Really?! Naruto Aniki?!"
"Of course-"
Naruto rinsed his mouth with water, then continued.
"In that mode, every Devil Fruit user on this sea would have to kneel before you."
"Wow!!!"
Stars sparkled in Konohamaru's eyes.
"Even Instructor Bullet wouldn't be my opponent?"
From this sentence, it wasn't hard to see that Douglas Bullet indeed didn't have much teaching talent.
Or perhaps his 'educational methods' were slightly too crude.
In any case, Konohamaru, his first student, upon potentially gaining a new ability, first thought was whether he could defeat his instructor.
-Or perhaps, this also counts as a good teacher?
"Right! He wouldn't be your opponent either."
Naruto's smile was subtle.
He seemed to foresee a future day when a fully combined Bullet would be drenched and defeated by a wave of water impact.
"Great, great! Naruto Aniki, teach me quickly!"
"Not so fast... ugh... Let's deal with the last troublesome one first... ugh... then we'll talk."
After saying this, Naruto leaned over the bow again, starting to, uh, 'chum the water'? Seeing this made Karin's eye twitch.
"Naruto-san, in your current state, are you still going to deal with that Imu?"
Imu's lackeys were basically all dead. Only a few stragglers remained. If they went to Mary Geoise now, the only one they'd need to deal with was Imu himself.
"When eliminating evil, be thorough. That's a lesson I've learned from experience over the years."
Naruto wiped his mouth, saying weakly.
It was clear the Naruto of the past had acted rashly without considering consequences, unlike now, where he plans ahead and aims to uproot problems.
These were lessons learned in blood.
After all, the sea was full of all kinds of people.
There were many heroes like Roger and Whitebeard, but also many pure villains like Doflamingo.
They wouldn't refrain from taking revenge just because you spared them.
In fact, even if they couldn't beat you, they might choose to take revenge on the ordinary people you had helped.
"But your body..."
Karin was more concerned about whether Naruto could still fight.
"It's fine. I'll be okay after some rest. Karin, adjust the direction according to this Log Pose."
Saying this, Naruto waved his hand and walked back into the cabin.
Thump!
Sasuke, who had just bumped his head on the mast, walked over as if nothing happened and said to Karin,
"If you can't do it, I'll take over."
He reached for the Eternal Pose pointing to Mary Geoise, but Karin dodged him.
"Better not. With your current luck, you might just sink the ship."
Hearing this, Sasuke didn't get angry. He shrugged and went to sit somewhere else.
So, under Karin's helm, the Gale Breaker sailed towards the endpoint of the first half of the Grand Line.
The Red Line!