After Rayleigh's "cruel" experiments, they confirmed his theory: the more severe the injury, the more stamina Shirakawa needed to heal. Minor scrapes barely used any energy at all.
Shirakawa lay on the floor, sweating profusely. He hadn't done any physical activity, just been repeatedly injured, yet he was exhausted, both physically and mentally.
"I've decided on your training regimen," Rayleigh said, sipping his wine.
"What is it?" Shirakawa asked, excited despite his fatigue. This was the start of his journey to become stronger.
"Simple. See all that equipment? Use it. Train your body and increase your strength. Two birds with one stone."
"..." Shirakawa waited for more, but Rayleigh remained silent.
"That's it?" he asked, incredulous. "That's too irresponsible!"
"Irresponsible? Don't worry. I'll supervise your training and make sure you don't slack off. If I catch you being lazy... well, you can imagine the consequences," Rayleigh said with a smirk.
'Sadist,' Shirakawa thought.
Suddenly, Rayleigh whacked him on the head with a wooden stick.
"Ow! What was that for?" Shirakawa complained, even though the pain vanished quickly.
"For insulting me in your thoughts," Rayleigh replied calmly.
"I didn't!"
"Still denying it?" Rayleigh raised the stick again.
"You think I can sense Conqueror's Haki but not your thoughts? I might not know exactly what you're thinking, but I can tell if it's positive or negative."
Shirakawa's eyes widened.
"How did you know what I was thinking?"
"A lucky guess," Rayleigh shrugged.
'That's incredible,' Shirakawa thought. He hadn't realized Rayleigh had that ability when watching the anime.
"Don't underestimate me, kid," Rayleigh said, his arrogance a stark contrast to his future self. "Now, start training. Any exercise will be beneficial for you at this stage."
Rayleigh sat down on a chair, watching Shirakawa intently.
"What about Shanks?" Shirakawa asked.
"He's still asleep."
Shirakawa chuckled awkwardly.
"You also need to teach me to control my Conqueror's Haki," he said.
"Of course. You shouldn't waste such a powerful ability. And if you accidentally unleash it during a fight and hurt our own crew, you'll be in big trouble."
For the next two months, Shirakawa endured Rayleigh's rigorous training. Even the rest of the crew suffered from Shirakawa's unintentional bursts of Conqueror's Haki. Rayleigh pushed Shirakawa to his limits, constantly triggering his Haki to help him gain control.
Finally, Shirakawa mastered his Conqueror's Haki, able to control its intensity and target. He had also improved significantly in strength, speed, and stamina.
While he lacked fighting skills, his immortality made him a formidable opponent. As long as he wasn't afraid of death, anyone with similar strength would struggle to defeat him.
However, Shirakawa remained humble. He trained against Rayleigh every day and still couldn't land a single hit. He had gone from being instantly defeated to lasting three moves, but he still had a long way to go.
'If only my stamina could increase too,' he often thought. Although his stamina didn't decrease, it also didn't improve.
Over these two months, Shirakawa witnessed the unpredictable weather of the New World firsthand. Clear skies could turn into thunderstorms, blizzards, or anything in between within moments. He saw the raw power of nature and understood why pirates feared it.
During one storm, a massive waterspout threatened to tear the ship apart. Rayleigh calmly unleashed a powerful sword slash, cleaving the waterspout in two.
Shirakawa was awestruck. He didn't know if Rayleigh had used his full strength, but the display of power left a lasting impression.
One day, while Shirakawa was resting, he heard hurried footsteps outside the training room.
'Another storm?' he wondered, as bad weather usually caused such commotion.
"First Mate, what's going on?" he asked Rayleigh.
"That mad dog is here again," Rayleigh said with a wry smile.
"Mad dog? Who?" Shirakawa was confused. The past two months of intense training had left him a bit disoriented.
"Just come with me and see."
Shirakawa followed Rayleigh outside. The crew was preparing for battle, the atmosphere tense.
'What kind of enemy could make the Roger Pirates so serious?' Shirakawa thought.
He followed Rayleigh to the bow of the ship and saw a distinctive dog-headed warship approaching them.
"Vice Admiral Garp," Shirakawa said in surprise.
That ship's design was unmistakable. It could only belong to Garp, the Hero of the Marines.