One Piece: The user of the Nen-Nen Fruit, who overturned the sea.

A three-month observation period sounds long,

But in a place like Beehive Island, time flies by like water.

Dr. Gracia practically lived in the lab, spending all his time outside of eating and sleeping monitoring the data of Subject Seven.

Blood pressure, heart rate, cell activity, gene sequence stability, and energy consumption curve.

His assistants were exhausted; one young man had worked overtime for three days and three nights in a row.

He fell asleep right next to the lab bench, his head hitting the keyboard and typing out a string of gibberish.

Fortunately, the outcome was good.

The genetic sequence of subject number seven showed no signs of collapse during these three months.

Whether he has two abilities or three, his body is like a precisely tuned machine, with all the gears meshing perfectly.

The three modified hearts were even stronger than normal hearts under such high-intensity loads, beating at a steady, metronome-like frequency.

Gracia then selected five more test subjects to test the compatibility of fruits of the same type.

The results are clear—zoo-types can eat each other without any problem, and paramecia-types can eat each other without any problem, but there are slight genetic fluctuations when combining natural-types with other types.

The fluctuations were not significant enough to cause a collapse, but Gracia still decided to hold back for now.

In his final report to Roy, he wrote a line in bold:

"We do not recommend stacking natural elements at this time; further observation is needed."

In addition to Devil Fruit compatibility, Gracia also focused on testing the stamina consumption multiplier for multiple Devil Fruit abilities.

The data is clear—using two abilities simultaneously consumes twice the energy of a normal state.

Using all three abilities simultaneously consumes three times the stamina.

This multiplier will not change based on the strength of the user's physical abilities; it's like an ironclad rule that no matter how strong you are, you have to follow this rule.

"This is indeed a big problem for ordinary ability users."

Gracia adjusted his glasses during the briefing.

"But for the core members of Beehive Island, this level of consumption is completely within their tolerance range."

Barrett's maximum combat endurance is about six hours, and even with triple the consumption, it can still sustain two hours of full-power output.

Two hours—enough time for him to smash ten naval bases.

After reading the report, Roy didn't waste any more words and directly asked Stella to arrange the transplant schedule for the core members.

The scheduling order is based on combat style, from simple to complex—first, let members with simpler combat styles perform the transplants to accumulate experience.

Then gradually advance to core combat capabilities at the level of Barrett and Hawkeye.

The entire process is expected to take three months, exactly the same length as the observation period.

The data from the successful experiment were laid out on the table, a thick stack, with more than forty pages of comparative gene sequence diagrams alone.

Roy went through the documents from beginning to end, examining every single piece of data very carefully.

He wasn't a scientist, but after spending so many years on Beehive Island, he had learned quite a bit from what he saw and heard.

The genetic sequence of the seventh test subject was incredibly stable, and the three hearts in the chest cavity each performed their own function, beating at a frequency as precise as a metronome.

Three months of high-intensity stress testing showed no signs of genetic breakdown.

But there is a problem.

Roy closed the file, leaned back in his chair, and tapped his fingers lightly twice on the table.

This was his habitual gesture when he was thinking, and Stella knew what he was planning every time she saw him do this.

"Call the doctor over here," Roy said.

Stella put down the coffee pot she was holding and glanced at him.

Roy's expression was calm, but after following him for so many years, she could see a hint of hesitation in his eyes that was unusual.

"Now?"

"Now."

Gracia arrived quickly.

The old doctor was in a great mood lately, walking with a swagger. When he entered the office, he was holding a newly printed data report in his hand, and the excitement on his face hadn't faded yet.

"Captain, what new ideas do you have now?"

I happen to have a few new hypotheses about the compatibility of natural systems—

"PhD."

Roy interrupted him, his tone a few decibels slower than usual.

Are there any other options besides a heart transplant?

Gracia's excitement suddenly froze.

He pushed up his glasses, looked at Roy's expression, and slowly put down the report in his hand.

"You mean, no open-chest surgery?"

"right."

Roy stood up and walked to the window.

The port outside the window was as bustling as ever. New recruits were running laps on the training field, merchant ships were loading and unloading cargo at the dock, and the chimneys of the weapons factory were emitting wisps of gray smoke.

Everything was in perfect order, but that wasn't what he was thinking about at the moment.

"Your report clearly states that to accommodate multiple Devil Fruits, a specially cloned heart must be implanted within the body."

The black beard's genetic sequence allows the body to accept these foreign organs without rejection, but the heart itself doesn't grow out of thin air.

"That's right." Gracia nodded.

"In other words, whoever wants to eat the second Devil Fruit..."

They all have to have their chests cut open and a cloned heart sewn inside.

"To be precise, it's two."

Three fruits require two additional cloned hearts,

Gracia added, his tone carrying the rigor characteristic of a scientist.

"Blackbeard himself has three hearts, so he can hold two additional Devil Fruits."

Our experimental subjects were also modified according to this structure.

Roy turned to look at him: "Besides open-chest transplantation, are there any other options?"

Gracia was silent for a few seconds, then shook his head.

"Captain, the power of a Devil Fruit resides in the heart; this is a fundamental rule of the pirate world."

A person has only one heart, so it can only hold one ability.

The reason Blackbeard was able to break this rule was because his physical structure was inherently different—he had three hearts.

"Our gene-editing technology allows ordinary people to receive multiple heart transplants without experiencing rejection."

But the only way to get these hearts into the body is through surgery.

You have to open up the chest cavity, put the cloned heart in the right place, connect the blood vessels, and establish a circulatory system.

There are no shortcuts.

Roy tapped his fingers twice on the windowsill; he knew the doctor was telling the truth.

Genetic modification only solves the problem of "whether it is acceptable," but the problem of "how to put it in" can only be solved by surgery.

"What about the risks?"

"Almost zero."

Gracia answered quickly.

"The cloned heart was cultured using your own cells, and the DNA is a perfect match."

Vascular anastomosis, performed using Beehive Island's medical technology, has a near 100% success rate and does not cause any rejection.

The entire process, from opening the chest to suturing, will not take more than two hours.

Roy didn't say anything after listening.

The office was quiet for a while, with only the old-fashioned clock on the wall ticking away.

He knew the doctor was right.

Beehive Island's medical technology is top-notch in the entire One Piece world, and cloned organ transplantation was already a mature technology three years ago.

Soldiers who lost limbs in battle, as long as they survived, could be returned and given a brand new cloned limb.

Although heart transplants are more complex than limb transplants, for Gracia's team it's just a matter of taking a little more time.

But knowing it is one thing, actually having someone cut open your stomach and stuff an organ into your chest cavity is an incredibly unpleasant thought.