"Your understanding is heaven-defying, and through the counter-shock force produced by hitting the target, Conqueror's Haki has been improved!" The words in his mind made Ace's eyes twinkle with excitement. As expected of the protagonist from the original work, Luffy could enhance his Conqueror's Haki.
In previous training with Garp, Ace had naturally awakened both Armament Haki and Observation Haki. Later, during a session with Sabo, Ace discovered that using Haki to hit Sabo could strengthen his Armament Haki. This realization was due to his exceptional understanding, allowing him to grasp the counter-shock force generated by Haki strikes.
Ace tested this on various gangsters at the Grey Terminal and even on the Dadan family, but saw no significant results. He concluded that only those with extraordinary talent could enhance Haki through such means. Ace had beaten Sabo for five consecutive days before reaching a limit, after which Sabo's strength was qualitatively improved through intense training. This allowed Ace to once again gain enhancements in Armament Haki by hitting Sabo.
Ace had been eagerly awaiting Luffy's arrival, and Luffy did not disappoint. Luffy's presence could enhance Ace's Conqueror's Haki. For Ace, physical enhancement came easily through combat breathing techniques and complete absorption, which in turn increased the power of the Mera-Mera Fruit. Armament Haki and Observation Haki could be continuously enhanced through practice and combat. However, Conqueror's Haki, a special power, could only be strengthened by the owner's increase in power. The ideal method was to challenge strong opponents on the sea, but Ace wasn't ready to venture out yet.
Now, with Luffy, everything changed. Luffy could enhance Ace's Conqueror's Haki. Ace noticed Luffy's pupils starting to flash red.
"It hurts so much! It hurts as much as Grandpa's fist! No, it hurts more than Grandpa's fist. I'm a rubber man who ate the Rubber Fruit. Why is this happening? Moreover, Ace, your fist didn't even hit me!" Luffy screamed, covering his head.
Ace looked at the howling Luffy, unsurprised. No matter how tough Garp was, he wouldn't beat Luffy with Conqueror's Haki. There was no comparison between pure Armament Haki and Conqueror's Haki.
"Rubber Fruit? Ace, this guy ate the same type of Devil Fruit as you? But why is he so weak?" Sabo asked, surprised.
"Huh? Ace, did you eat a Devil Fruit too?" Luffy was shocked, then overjoyed. Finally, he wasn't the only one who had eaten a Devil Fruit.
"Yes, Ace is the Flame Man who ate the Mera-Mera Fruit. It's much stronger than the Rubber Fruit you ate," Sabo said proudly.
"Flame Man?! So awesome! But Sabo, why are you so proud?" Luffy looked at Sabo curiously.
"Mind your own business!" Sabo snapped.
"We'll talk about Devil Fruits later. Luffy, if you want to join us, this ritual is indispensable. But if you're afraid of pain, then sorry," Ace said with regret.
"No! As long as we can be friends, this pain is nothing! Come on, Ace!" Luffy said eagerly, envisioning a bright future with Ace and Sabo.
"Oh? Then, I'll continue." Ace's eyes flashed red. If Luffy was still eager to be beaten, Ace wouldn't hold back as Orangle-Black Lightning coated his fist while sparing no mercy.
"Bang! Bang! Bang!"
"Ah!!!" Luffy's screams echoed through the jungle.
"Your understanding is heaven-defying, and through the counter-shock force of hitting the target, Conqueror's Haki has been improved!" The pleasing words kept reappearing in Ace's mind.
Three months passed quickly. Ace's life during this time was a routine of eating, sleeping, and "Training" with Luffy. Although Luffy often took several days to recover from the beatings, he was always eager for more. Each beating made Luffy feel closer to becoming friends with Ace and Sabo. This intense training improved Luffy and Sabo's strength much faster than in the original story, which in turn helped enhance Ace's Haki.
Eventually, Luffy could no longer provide further improvement for Ace's Conqueror's Haki, but Ace's Conqueror's Haki had doubled in strength. Ace couldn't help but acknowledge Luffy's extraordinary potential.
"Very well, Luffy, you only have one last test left to join us," Ace said, looking at Luffy, whose face was swollen and bruised beyond recognition. Sabo, though not in much better shape, also looked happy. Their strength had improved significantly through Ace's beatings.
"Really?!" Luffy's voice was slurred from his swollen face, but he was visibly excited.
"That's right," Ace nodded, then looked at Sabo. "You want to become a pirate, right? The first step is to Loot. Sabo will take you to do it."
"I don't only want to be a pirate, I want to be THE Pirate King!" Luffy exclaimed.
"One Piece? Then, let's take the first step," Ace said, signaling to Sabo.
"Let's go, Luffy. I'll take you to do something. We still need more to buy a pirate ship," Sabo said.
In the past three months, although Sabo didn't say much, he had come to recognize Luffy's tenacity.
"Okay!" Luffy said excitedly. "By the way, Ace, aren't you coming?"
"If Ace goes, it won't be a test, idiot!" Sabo retorted, grabbing Luffy and heading towards the Grey Terminal.
Ace lay back, basking in the sun leisurely.
Two hours later, Luffy came running back, shouting, "Ace! Look how much we got!"
"It's really a lot of loot," Ace remarked, a slight smile on his face. The amount they had taken was significant, not something ordinary gangsters would possess.
"It's a big step towards buying a pirate ship!" Sabo said excitedly, full of anticipation for their future.
As they celebrated, a giant man with a machete and several minions approached. "Hey, the guy who robbed you is named Sabo? He often hangs out with a kid named Ace?" the man asked.
"Yes, they are quite famous," one of the minions confirmed.
"Ace, we seem to have grabbed someone we shouldn't have. They're Mr. Blue's men," Sabo said, sweating nervously.
"Luffy, why were you caught?!" Sabo stared in disbelief as Luffy was captured by Jamie Burl.
"Do you know Ace?" Jamie asked coldly.
"Yes! We are friends!" Luffy shouted.
"Oh? Then you must know where Ace is, right?" Jamie asked, a sinister smile on his face.
"I, I don't know," Luffy stammered.
"Very well, I'll make you tell me," Jamie sneered, grabbing Luffy and walking away.
"Hey! Ace, what should we do? Do we save Luffy?" Sabo asked anxiously.
"Of course, but we need to move the treasure first," Ace said casually, having already locked onto Luffy with his Observation Haki.
"But... but..." Sabo hesitated, looking at the treasure.
"Let's go rescue Luffy. We can get the treasure later," Sabo decided firmly.
"Then let's go rescue him," Ace said, smiling at Sabo's determination. "But if you want to save him, you have to listen to me."
In a secluded cabin, Jamie Burr relentlessly beat Luffy with iron-jab gloves. Luffy, already on the verge of collapse, refused to reveal Ace's location.
"I won't tell you where Ace is! And this fist is nothing compared to Ace's!" Luffy shouted defiantly.
"Oh?" Jamie's face darkened as he hit Luffy harder. Eventually, Luffy was too weak to speak.
"Boss Jamie, forget it. This kid won't talk," one of the minions said, unable to watch anymore.
"If he doesn't talk, he dies," Jamie said, raising a machete.
At that moment, the door burst open. Ace, moving like an afterimage, rescued Luffy. "Boss Jamie, that's Sabo and Ace!" the minions shouted.
"You are very brave," Jamie said, smiling ferociously.
"Ace, Sabo, you came to save me? Are we friends?" Luffy asked weakly, smiling at Ace and Sabo.
"Luffy, haven't you always wanted to see my power?" Ace asked calmly. "Look, this is the power of the Mera-Mera Fruit.
Fire Fist!"
Roaring flames engulfed Jamie and his men, reducing them to charred remains in an instant.
"Is this... Ace's ability? Ace is so strong," Luffy murmured, staring at the charred remains and feeling the heat in the air.
Outside the cabin, Ace looked at Luffy. "Sabo and I didn't come to save you right away. What do you think about that?" Ace asked.
"What do I think? Of course, I thank you for saving me! And Ace, I trust you had your reasons. I support you unconditionally," Luffy said, smiling.
"Is that so?" Ace smiled back. "Sure enough, he's a fool, but I really don't hate this kind of idiot. This whole ordeal was to improve Luffy's ability. Conqueror's Haki can only awaken in dire situations, and this incident was a rare opportunity."
Sabo also smiled. He unconditionally supported Ace's decisions, knowing Ace was never wrong.
"Hey, Luffy," Ace said seriously. "We don't want to be friends with you anymore."
Luffy was stunned. "Let's be brothers," Ace said, smiling brightly.
"Yeah!" Luffy exclaimed in surprise and joy.