As the submarine continued travelling across the calm stretch of sea, John enjoyed another period of uninterrupted movement.
The automatic defense system that he had installed around the hull performed exactly as he designed it to, eliminating any sea kings that tried to bite into the vessel.
Their movements reminded John of the way Rayleigh once swam to the Kuja Island, although John had no intention of letting the corpses drift away uselessly.
Sea kings provided an enormous amount of meat, and the protein and nutrients inside them were important not only for Bullet's rapidly growing body but also for maintaining Narberal's strength, since both of them needed large quantities of food to support their increasing physical demands.
"Your cooking is really great, Captain. This is delicious," Bullet said with his usual enthusiasm, chewing on a piece of meat that almost looked too large for his small hands.
John learned how to cook from Vegapunk's mother, spending many hours watching her prepare meals while he stayed in their home.
It became a habit for him to cook for the three of them as a way of showing gratitude for what he had learned during those days.
"Good. Eat a lot, Bullet. A growing man needs enough food so his body has energy to become stronger," John told him. Bullet nodded with a large smile and immediately started eating faster.
Narberal ate more calmly beside them, but even he showed an expression of satisfaction, as he had grown used to this peaceful routine throughout the past year.
Once they finished eating, their daily training began. Narberal usually sparred with John, while Bullet practiced the basic regimen John designed for him.
At the same time, John used these sessions to refine the martial arts concepts he had been organizing in his mind.
The first styles he focused on were the Gaoh Style and the Niko Style, which were used by the main character of one of the mangas he remembered from his old life.
John recalled every detail of how the styles worked, including the emphasis on muscle control, breathing, and posture.
Many of these principles overlapped with the Rokushiki techniques, especially the muscle hardening that resembled Iron Body, except without the drawback of being unable to move.
Narberal launched the first attack, pressuring John with a series of fast movements. His fists ignited with fire as he approached, and the flame on his back activated the moment the fight began.
John sensed all of this through his observation and stepped forward to meet him head on. Narberal extinguished his back flame for an instant as he attempted to reposition, then reignited it to activate his natural Lunarian invulnerability.
Normally, this state made him immune to any physical attack, but the effect failed whenever he fought John.
Narberal felt the force of John's punch travel through his body, something he still struggled to understand. No matter how many times they sparred, John's strikes always managed to bypass his natural defense.
John's raw physical strength, combined with his precise muscle control and unusual biology, simply overwhelmed the limits of Lunarian durability. Even without haki, John struck harder than most people could imagine.
John followed up with the first technique he intended to incorporate into his new martial system. It is called Ironfingers, a variation of the Iron Body concept, where he tightened the muscles and joints in his fingers until they became dense enough to generate extreme penetrating force.
When he struck Narberal's chest, the blow was strong enough to extinguish the flame on his back entirely. The impact launched Narberal across the room until he collided with the far wall of the training area.
Narberal pushed himself up a moment later, with a visible dent on his chest and blood at the corner of his mouth. Despite the damage, he looked at John with an expression filled with genuine admiration.
"It is incredible that you are this strong, even though you are still so young," Narberal said. John answered with a small smirk.
"Aren't you the same age as me?" John replied. Narberal did not argue, but the look he gave made it clear that he acknowledged the truth. They were the same age, yet he, as a Lunarian, was being tossed around by John even when John was not using his full strength.
After that exchange, the spar continued, with John maintaining steady pressure and Narberal adapting to the rhythm of each attack.
Meanwhile, Bullet followed his own training routine on the side. He was practicing by repeatedly stabbing his finger into a bowl filled with iron sand, an exercise that helped strengthen the fingers and develop precision. The routine was something John introduced to him to build a foundation for future techniques.
The three of them trained like this every day, developing a rhythm that allowed all of them to grow stronger in their own ways.
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After a full week of uninterrupted travel through the Calm Belt, the submarine finally crossed into the waters of the South Blue.
The moment they left the stillness of the Calm Belt and entered the natural currents of the open sea, the vessel began to sway gently, a reminder that they had reentered the world of regular ocean movement.
John continued steering while maintaining his daily routine with Narberal, and their sparring sessions grew more refined each day.
John spent the entire week polishing every part of the martial arts system he had been shaping, trying to merge what he remembered from Gaoh Style and Niko Style with the principles of the Rokushiki.
Throughout that week, he wrote down every technique, concept, and adjustment into a manual.
His goal was to create a structured guide so that once Narberal completed his Rokushiki training, he could immediately begin learning the additional martial arts that John was forming.
John wanted the system to be something that would grow with them over time, not just something they practiced without direction.
Narberal also improved significantly. The combined effect of John's intense training method and Narberal's own determination pushed him to grow at a much faster rate than when he trained alone.
When Narberal realized how fast he was progressing, he asked John to stop holding back during their sparring sessions. John agreed and increased the force he used, though not to the point of causing permanent injury.
This naturally resulted in Narberal being defeated far more quickly, but with the healing ability John had granted him and his personal commitment to rise after every failure, Narberal never stayed down for long.
Every time John knocked him down, Narberal forced himself back to his feet. Every injury recovered faster than a normal person's thanks to the enhancement John provided, yet the effort needed to stand up and continue was still entirely Narberal's.
John respected that. In a way, Narberal's stubbornness reminded John of certain characters he admired in his past life, individuals who refused to give up no matter how overwhelmingly strong their opponents were.
A short time after entering the South Blue, John noticed an island appearing in the distance. The dark silhouette gradually grew clearer until the coastline was visible.
Since they had been confined to the interior of the submarine for an entire week, all three of them felt the boredom slowly accumulating. Once they were close enough, John decided they would dock for a short break.
When the submarine surfaced and settled near the shore, the three of them stepped outside. The fresh air of the South Blue felt comforting after the long period of living inside metal walls.
They walked along the coastline together, simply appreciating the open space and the chance to stretch their bodies under the sunlight that the Calm Belt rarely provided through the water.