Internal Combustion Engine

Junkyard Island.

Tom, Iceburg, Franky, and Yokozuna, a large blue frog—three men and one frog—stood before a steam locomotive.

It was the result of three days of assembly work.

Franky excitedly hugged Yokozuna, the frog, and shouted joyfully:

"Mr. Tom!

Great! We've assembled the locomotive.

Now, as long as we get it running on the tracks over the sea, we'll have succeeded!"

"Hahaha! It's still too early for that! Let's test-run it first!"

Laughing, Tom wrapped both arms around the locomotive.

To test whether the train could run over the sea, the three of them had already built a short stretch of track near the shore of Junkyard Island.

With the terrifying brute strength of a bullhead Fish-Man, the steam locomotive, weighing over a hundred tons, was effortlessly lifted and placed at the starting point of the tracks.

Before Tom could give an order, Franky's eyes gleamed as he eagerly volunteered:

"Mr. Tom, let me drive this train!"

"Hahaha! Looks like you can't wait any longer. Then you can start it up!"

Franky grinned and dashed into the locomotive's engine room, where he began shoveling in coal and lighting the fire.

Moments later, billowing black smoke rose from the steam locomotive. Amid a thunderous "Thump, thump, thump!" it slowly began to move, while its metal wheels spun faster and faster.

However...

Before the steam locomotive had even traveled twenty meters, the entire engine uncontrollably tipped into the sea. Franky hastily abandoned it and jumped into the water, narrowly avoiding being buried beneath the waves.

Seeing this, Tom immediately jumped into the sea with a "Splash!," sending up a huge spray of water.

He was not going to save Franky. He knew the latter's swimming skills very well; as long as Franky was not thrown into some massive ocean whirlpool, he could basically swim back alive and kicking.

The one Tom wanted to save was the steam locomotive!

If one steam engine had to be scrapped every time they failed, his wallet could not withstand that kind of waste!

The Fish-Man Race were beloved by the sea. Compared to land, the ocean was where they could fully unleash their racial talents.

Very soon, Tom emerged from the seabed, carrying the steam locomotive on his shoulder as he climbed ashore.

Franky, who had just swum back to shore, shook his drenched blue hair and said helplessly:

"Mr. Tom, didn't you say the locomotive you built could travel on the sea?

Why did it tip into the water...?"

At that, Tom immediately laughed and scratched his head.

"Ahahaha! There's nothing we can do about that...

This happened because the buoyancy of the tracks and the locomotive's flotation system isn't enough, and also because the Sea Train isn't fast enough...

It's really been troubling me!

If the steam engine's efficiency could increase from eight percent to more than fifteen percent, it should be able to reach a state of balance, right?"

"What if we used another machine to provide power, one with an energy efficiency of more than twenty-five percent, or even as high as forty percent?"

Hearing that somewhat familiar voice, Tom turned around in surprise and looked toward Sephiroth, who was slowly walking over from afar.

"If that were the case... that would be truly incredible!

Maybe the Sea Train could travel directly over the sea, hahahahaha!"

"Oh? Then I think you'll be very interested in this."

Sephiroth unfolded a blueprint he was holding in front of Tom.

Although the blueprint in his hands was crude and almost entirely lacking in details, it was already everything he had managed to recall after racking his brains over the past few days...

"Could you explain how it works?"

Shipwright Tom looked at the mechanical schematic in the boy's hands, along with the rough cross-sectional diagram of an Internal Combustion Engine, and could not help sinking into thought.

He had boldly promised a judge that he could build a Sea Train connecting multiple islands within ten years.

That was because his mechanical engineering expertise was exceptional. He knew that as long as he overcame several technical hurdles, he could turn the Sea Train into reality.

Therefore, the instant Shipwright Tom saw this Internal Combustion Engine blueprint, he understood many things.

"This is a heat engine that uses diesel as fuel and converts thermal energy into power..."

Sephiroth explained as thoroughly as possible the knowledge about Internal Combustion Engines that he had learned in high school to the greatest shipwright in the world of the Pirate King, hoping the other man could understand this machine as soon as possible.

Franky forced his way over and listened to Sephiroth's explanation from the side. Once it was over, an excited smile immediately appeared on his face.

"Mr. Tom, this thing is so interesting! I think we can give it a try!"

"Hahahaha! This is really unbelievably amazing!

Young man, you're willing to tell me the principles behind such a machine. You're truly an incredible man!"

Even Franky could understand it, so Tom, his teacher, naturally had no trouble understanding it even more thoroughly.

"Young man, could you show me the blueprints with the dimensions for the relevant parts?"

Sephiroth decisively shook his head and casually brushed him off:

"I don't have anything like that. I only came up with this on the spot."

As a surgeon, if someone wanted to discuss medicine with Sephiroth, he could certainly talk at length and explain it with great confidence.

But...

Mechanical engineering?

Every field had its own depths. It was already impressive enough that he could draw a rough schematic of an Internal Combustion Engine. Asking him for dimension drawings of the parts was really asking too much!

"Oh! I see! Even so, you're still very impressive, young man...

By the way, what is this machine called?" Tom asked with a smile.

"An Internal Combustion Engine."

After discussing the Internal Combustion Engine with Tom, Sephiroth rode Arrowfish toward home.

Leave professional matters to professionals.

Regarding the Sea Train project, that was all he could do.

Of course, he had gained something extra as well. At the very least, he had earned favors from Tom, Franky, and Iceburg.

If he needed their help in the future, given their personalities, they would probably lend a hand as long as it was not too troublesome...

When Sephiroth returned home, a guest was already waiting in his living room. The three Boa sisters sat on the sofa nearby, keeping the guest company as they waited for him to return.

The guest was Hughes Shilke, president of Hughes Shipbuilding Company. He was a red-haired middle-aged man with a sturdy build, rugged features, and a sharp black suit.

"Sephiroth, it really is you... It's wonderful that you're safe!

I heard the passenger ship you were on was attacked by pirates...

By the way, where is your father, Pal?" Hughes Shilke asked excitedly.

"He was killed by pirates while protecting me..."

As he spoke, Sephiroth let out a soft sigh, his eyes growing somewhat dim.

The man named Karl D. Pal had been a great father, willing to sacrifice his own life for his son.

Karl D. Sephiroth's mother had died of illness not long after he was born, leaving his father to raise him alone.

Therefore, in the original owner's heart, his father had been the most important person in the world...

Hearing that, Hughes Shilke also sighed softly. He looked at Sephiroth and said solemnly:

"How about this... Sephiroth, why don't you come work at the shipbuilding company from now on?

Although business isn't doing well right now, you'd at least have a stable income if you worked for the company..."

"No, thank you for the offer, Uncle Shilke. To be honest, I'm planning to join the Marines..."

Upon hearing this, the three Boa sisters beside him immediately shouted in unison:

"The Marines!!!" ×3

"Sephiroth, why do you want to become a Marine?" Boa Hancock frowned slightly, her tone full of confusion.

"Because... I don't just need strength. I also need an organization capable of rivaling the Beasts Pirates if I want revenge...

Joining the Marines is my best option right now."

Sephiroth lowered his eyelids. His expression revealed neither joy nor anger, but his tone was exceptionally resolute.

The Marines in the world of the Pirate King had been established by the World Government, specifically to serve the nations affiliated with the World Government and the world's nobles.

The Marines had no authority to interfere in another nation's internal affairs, much less defy orders issued by the World Government. Their duty was merely to maintain order on the seas, strike against pirate forces, and do some dirty work for the World Government. Sometimes, when Celestial Dragons killed people, the Marines even had to help set the fires...

Still, despite all the restrictions and flaws of the Marines, it was undeniable that they possessed a highly mature system for training talent.

After all, through this period of training, Sephiroth had come to realize that while he did possess Conqueror's Haki and the Mythical Zoan Vampire Fruit, he had no systematic method of becoming stronger and could not bring out their greatest potential.

As a result, even if he spent ten hours a day training, he only felt a slight improvement in his physical abilities. As for combat experience, he was still practically a blank slate...

This world had never lacked top-tier powerhouses who had grown through endless slaughter—Roger, Kaido, Charlotte Linlin, Edward Newgate...

But...

Compared with learning through trial and error, Sephiroth, who had received a systematic education in his previous life, trusted formal training more. The Marines were one of the more reliable options.

"I see... Both strength and influence are necessary..."

Boa Hancock murmured softly, deep in thought.

Seeing this, Hughes Shilke rose from the sofa, gently patted Sephiroth's shoulder, and sighed.

"Sigh! Sephiroth, since you've already made your decision, I won't try to persuade you any further.

If you ever need my help in the future, come find me..."