He trained them like that for a while, ignoring the fact that Robin, in fact, was able to see through him.
He acted as if he wasn't trying his hardest to hide the fact that she saw through him and all that shit.
By the third day mark...
Luffy would wake up.
"MEAT!"
That was his first thought—he wanted meat, and a lot of it.
Luckily, since Kairo knew his captain was a glutton, he had hunted a sea beast nearby and had Sanji cook it. Sure, it was big, and yes, Sanji had to do it while evading the clone—training wasn't all fun and games.
"Here," Kairo would say, handing him the meat.
And Luffy would grab that shit, looking happy.
"Awesome... meat!" The captain would begin eating.
And eating.
And eating.
Kairo watched as Luffy ate... 40% of the sea beast by himself.
Luffy laid on the floor, looking stuffed.
He was truly just a glutton.
And once Luffy was stuffed and had his fill—
"Ussop... why do you look so beat up?" Luffy would question, looking at Ussop who was bandaging himself.
"...A sea beast attacked... so I showed him why they call me the great Captain Ussop," he half-lied.
Luffy's brow furrowed.
"I don't believe you." That wasn't Luffy. He believed lies way too easily. This wasn't him.
Kairo gazed at him, seeing the light smile on his lips and the red eye. They made eye contact before Luffy's eyes returned to normal.
"Ah..." Kairo couldn't understand how Ussop's face looked so goofy.
"He did deal the finishing blow," Kairo said calmly.
Luffy turned his head to Kairo, then to Ussop.
"Really!?"
Wow, he didn't expect Ussop to beat a sea beast.
Ussop would act as if this was expected of him.
"Well, of course. I am Captain Ussop."
"How did you do it? Tell me," Luffy seemed excited.
Ussop would point his finger at himself.
"The beast stood no chance! Once I spotted it, I simply launched my Super Sogeking Shooting Star Attack and it was defeated!"
Ussop was really making himself look better than he actually was.
Oh well, Kairo wouldn't take this bragging right away—he earned it.
While Luffy wondered what he meant, Ussop would put a ball in his weapon and fire it.
Once it was far away, Ussop would clench his fist... and in the air—a massive, and I repeat, a massive explosion could be seen, illuminating the sky.
Luffy's eyes were stars at this point.
Kairo simply looked at the explosion.
'He coats the projectile with his sweat, laces its core with his blood. When the outer sweat evaporates and scatters in the air, he triggers the blast — and the result isn't just a single explosion, it's everything tied to him igniting at once. The air itself becomes part of his weapon.'
If you want some in-depth explanation, shit would look like this:
The Core (Blood Charge):
Inside the projectile, Usopp mixes a small amount of his own blood into the stuffing or liquid core.
Blood is denser and more stable than sweat, meaning it stores his explosive potential longer before detonation.
When activated, the blood acts like a compressed energy node—igniting with high temperature and pressure.
The Shell (Sweat Layer):
Around the exterior, Usopp coats the ball with his sweat, which evaporates slightly mid-flight.
His sweat, being lighter and volatile, forms a thin mist trail that expands outward as the projectile travels.
Once triggered, every microscopic droplet reacts simultaneously—causing a secondary airburst effect.
Mid-Air Separation:
The projectile is engineered (or shot) so that, once it reaches a certain distance, the outer sweat layer peels off due to friction and heat.
This disperses the sweat into the air around the target zone, effectively seeding the atmosphere with explosive potential.
Detonation Command:
Usopp triggers the explosion (usually by snapping his fingers, shouting the command, or mental activation)—the core blood charge explodes first.
This initial explosion ignites the surrounding sweat particles, creating a chain detonation.
Amplified Explosion Radius:
Because both the sweat mist and blood core are tied to his body's composition, the explosion harmonizes instead of cancelling out.
This results in a multi-layered blast—the core explosion (high impact) + surrounding airburst (wide range).
The net effect: a much larger and hotter detonation zone than a regular bomb or pellet could ever achieve.
So yeah, it was a creative fruit.
Luffy was amazed Ussop had a Devil Fruit, and Ussop was flexing his shit.
Good for them. When Luffy was done with that, Kairo would say:
"Now that you're awake, we can start with your training," he said calmly, before tossing Luffy a pair of sea stone cuffs.
"From today, you will wear this for training."
"But doesn't this make me weaker? How am I supposed to fight when I can't throw a punch?"
Kairo would look at Luffy before saying,
"While yes, the cuffs do drain your energy, that is why you must wear them. Think of them like a cheat code to help you get stronger faster. The faster you get used to them while also being able to use Haki, the faster you will grow. Since you wanted to keep me so badly, this is the consequence. Now train like your life depends on it."
Luffy would grin at that—he regretted nothing.
And thus, for the following week or so, they trained like their lives depended on it. Kairo would push them all to the brink of death and let Chopper heal them. Chopper was putting in overtime—the amount of times he had to heal people was absurd.
Though, it was a perfect chance for him to learn Medical Ninjutsu—basically, how to use Haki to help facilitate someone's healing process and so on.
Kairo would be beating the brakes off them daily, not even giving them a day to rest—only letting them sleep at night, and even then, sometimes he would attack them too.
Shit was ruthless.
He would push them all to their brink, keeping them in a state of near death and fighting for their lives...
And this training regimen lasted for a month.
A/N would you rather a tontata girlfriend or a giant girlfriend.
So it's either you choose to feel big for the first time of your life or go cave exploring.
Vote wit powerstones