Dr. Brief, at the end of the day, is a scientist, not a martial artist.
His explanation of the "bloodline disease" is rooted in experimental data. But from a martial artist's perspective, it all boils down to one word: balance.
Whether it's the "ki" of the Dragon Ball world or the chakra system of Naruto, balance is everything—especially the balance between Yin and Yang. When Yin, representing mental energy, and Yang, representing physical strength, fall out of sync, all sorts of problems arise.
Take the Uchiha clan, for example.
Before reaching the three-tomoe Sharingan, Yin and Yang are generally balanced. Any genetic defects usually stay dormant, lurking in the body as a hidden ailment. But once the Mangekyou Sharingan is awakened, Yin energy skyrockets, overwhelming the body's physical capacity. This imbalance starts to show, with the body breaking down under the strain.
Even the Eternal Mangekyou Sharingan only prevents blindness—it doesn't eliminate the physical toll of using its techniques. It's a bandage, not a cure.
The real fix lies in Yang energy.
In other words, the "Sage Body" of the Senju or Uzumaki clans.
In theory, Dr. Brief's "targeted genetic serum" should mimic the effects of Hashirama or White Zetsu cells. But its actual effectiveness, and whether it needs further tweaks, depends on clinical results.
Uchiha Hikari plans to hand this over to Orochimaru for some localized refinements, then have Fugaku select clan members for testing. The first "test subject"—or rather, "clinical sample"—is obviously Itachi. His bloodline disease is the most pronounced in the entire Uchiha clan.
A copy of the results will also go to Orochimaru as a sort of "employee perk" from his boss, Hikari. Though, to be fair, Orochimaru's not drooling over Itachi's body anymore—he's got his sights set on Hikari's instead…
That night, Hikari and her group stayed at Bulma's house.
At Bulma's insistence, Hikari grabbed her bedding and bunked in the same room as her—a nod to the days last year when they traveled together searching for the Dragon Balls. Esdeath and Tanjiro, meanwhile, each got their own rooms.
Yamato had wanted to join Hikari and sleep in the same room, but her size posed a problem. Bulma had recently custom-made a bed for her, a massive four-to-five-meter-long monstrosity that wouldn't even fit through Bulma's bedroom door. So, Yamato had to abandon the idea.
That evening, Bulma dragged Hikari into a long, rambling chat. One moment she was reminiscing about their Dragon Ball hunt, the next she was updating Hikari on Goku and Master Roshi, then jumping to her plans for a pirate crew. It wasn't until the moon hung high in the sky that she finally quieted down, wrapped herself in a thin blanket, and drifted off to sleep.
The night passed without incident.
The next day, the weather was clear and bright.
After breakfast and a quick goodbye to the Briefs, Bulma tossed out a Capsule Corp airship, and the group set off toward Kame Island.
Among them, Hikari and Tanjiro were seasoned travelers, unfazed by the tech of the Dragon Ball world. But for Esdeath and Yamato, it was their first time in one of these vehicles. Yamato, in particular, had only ridden in cars before, which paled in comparison to this flying ship. She spent the whole trip glued to the window, marveling at the rivers and mountains below, letting out excited whoops every Hawkins.
Esdeath was more composed, but you could tell she was forcing herself to stay cool, clinging to her icy, proud warrior persona.
"So, Miss Bulma, that pirate ship you mentioned before… it's not gonna be one of these flying things, is it?" Yamato asked.
"Hm?" Bulma grinned. "I've been thinking about it, but I'm still figuring things out. Even if we add that feature, it'll still mainly sail on the sea. I mean, we're building a pirate crew, right? If it's flying around in the air, doesn't that kinda go against the whole pirate code?"
Hikari couldn't help but think, Pirate code? By that logic, wouldn't they have to go rob a few ships and pull off some big heists to really earn the "pirate" title?
But whatever.
The power system in the One Piece world isn't exactly weak, but their ships are mostly wooden, and pirates there tend to care more about their own strength or Devil Fruit powers than ship weaponry. Even if Bulma didn't outfit their destroyer with missiles or nukes, just equipping it with a solid cannon system…
Well, that'd probably be enough to shake up the seas with some serious firepower.
After a few hours of flying, the airship reached Kame Island, circled once, and landed smoothly on an open patch of ground.
Bulma, clearly no stranger to the place, stowed the airship back in its capsule and strode up to the small house in the center of the island. She gave the unlocked door a few casual knocks, pushed it open, and shouted, "Hey, you old perv, hiding in here watching your sketchy shows again?"
"?!"
Inside, Master Roshi was sprawled on the floor, one hand propping up his chin, grinning at the TV as a girl on-screen showed off some impressively flexible moves.
Bulma's voice startled him, but he quickly recovered with a cheeky grin. "Well, if it isn't Bulma! Been a while since you dropped by. And here you are, slandering my good name…"
"Good name? Please," Bulma snorted. "I'm here to see Goku and Launch, not you, you old lech. What 'good name' are you even talking about?"
She stepped inside, making way for the others.
Hikari followed, with Esdeath and the rest trailing behind.
The moment Roshi laid eyes on them, his eyes lit up. "Bulma, who are these lovely ladies…?"
"Tch, forgot already?" Bulma teased. "You met her last year, remember, old man? Right, Hikari?"
"Hikari?" Roshi tilted his head, thinking hard before it clicked. "Oh, you're that girl who was with Goku and the others hunting for the Dragon Balls! Your name was… uh…"
"Hikari. Uchiha Hikari," she said, introducing herself.
Compared to Bulma, Hikari wasn't exactly close with Roshi—just acquaintances. They'd met a year ago during the Dragon Ball hunt, and while Roshi had once jokingly offered to take her as a disciple (mostly because he was smitten), it was a passing comment, long forgotten.
Bulma took the lead, introducing everyone one by one.
As expected, Roshi's eyes gleamed with his signature lecherous grin when he saw Esdeath—until she shot him a glare laced with killing intent, making his eyebrows twitch and his smile turn a bit strained.
"So, this lady's a friend of yours and Bulma's, huh?" Roshi said, sizing up Esdeath.
With his experience, he could tell she'd seen blood—a lot of it.
Esdeath, meanwhile, was studying him just as closely, picking up on the faint aura of a seasoned fighter.
Finally, she spoke up. "Hey, old man. Wanna spar?"
"?"
Roshi blinked, caught off guard.
Hikari coughed and stepped in. "Master Roshi, this is Esdeath, a friend of Bulma and mine. She's a martial artist who loves a challenge and has heard of your 'God of Martial Arts' reputation. She'd like to test her skills against you, if you're up for it."
"Oh?" Roshi's expression grew a touch more serious. "'God of Martial Arts' is a title from way back. These days, I'm just a carefree old hermit. But… if you girls let me sneak a peek at your underwear, I might be persuaded."
"…You tired of living, old man?" Esdeath's voice turned icy, her killing intent practically tangible.
As the room's tension spiked, Hikari sighed, reached into her ninja pouch, and pulled out a manga, placing it on the coffee table. "Master Roshi, I know it's a bit forward to ask you to spar on short notice. How about this as payment? I've got plenty more where that came from, and they're all yours if you agree to fight."
"Hm?" Roshi picked up the manga, flipped through a couple of pages, and his breathing quickened. "Well, well, well… didn't expect you to have such good taste, young lady. Alright, I'll have a friendly match with this miss."
With that, the group moved outside.
Kame Island was tiny, barely a few hundred square meters, making it a bit cramped for a fight.
Roshi was about to pull out a small boat to head to the mainland when Esdeath walked to the island's edge, crouched down, and pressed her hands to the ground. "Haa…"
The power of the Demon's Extract surged.
In an instant, the blue seawater froze solid, the ice spreading rapidly across the ocean. Within moments, a dozen kilometers of sea had turned into a thick, solid plain—sturdy enough to run a train on.
"…A superpower?" Roshi's eyelid twitched.
He couldn't sense any ki from Esdeath, so he assumed it was something else.
The Dragon Ball world was no stranger to superpowers—General Blue's telekinesis, Chiaotzu's mind control, even Oolong and Puar's shapeshifting counted. But a power that could reshape terrain on this scale? That was rare.
"You could say that," Hikari nodded.
Over on the ice, Esdeath walked a short distance and turned, beckoning with a finger. "Come on."
Roshi stepped onto the ice, hands behind his back, standing calmly.
Esdeath struck first, closing the hundred-meter gap between them in a flash and throwing a punch!
"…So fast!" Roshi's eyes widened, but his body reacted instantly, ducking under the punch and sidestepping a sharp whip-like kick.
"Not bad," Esdeath said, a cold smirk curling her lips after confirming the old man had some real skill. "Guess I underestimated you. But looking at your frail old frame, you'd better not overdo it, or I can't promise you'll walk away in one piece."
"Heh, no need to worry about me, Miss Esdeath," Roshi replied lightly.
In the next few moments, Esdeath's punches and kicks came faster, a relentless storm of attacks. To onlookers, it was like she'd sprouted extra arms, her movements so quick they left afterimages in the air.
Roshi, by contrast, moved almost leisurely, his actions seemingly sluggish yet somehow dodging most of her strikes. The contrast—her blinding speed against his calm precision—was almost bizarre, leaving Bulma and Tanjiro wide-eyed, struggling to follow.
Hikari, however, had activated her Sharingan, closely studying Roshi's every move.
"…Is this a simplified version of Ultra Instinct?" she murmured.
To put it in perspective…
At this point in time, Roshi's strength was solid but not overwhelming. In the original story, his power level was measured at 139 during the Saiyan Saga, using Raditz's scouter in his normal state. When fully powered up, he could probably hit around 200.
That's a quirk of the Dragon Ball world. For martial artists with ki, power levels are just a baseline. Their actual strength can vary wildly depending on their state. Take Goku: starving, he could barely handle Yamcha, but well-fed, he'd mop the floor with him.
Right now, though, Roshi's been coasting for decades. In the original timeline, he struggled to beat Goku at the 21st World Martial Arts Tournament in a couple of weeks, and it took him three years of secret training to get back to a level close to Tien or Goku at that time. So, he's likely not even at 139 right now.
Esdeath's power is harder to pin down due to her different system, but with the Demon's Extract, she's probably in the 200-300 range, not far off from Piccolo Daimao.
That said, when it comes to pure physical technique, Esdeath's strength and speed outclass Roshi by a wide margin—but her skills are a step below his. Especially when he's using what seems to be a "simplified Ultra Instinct" or, in other words, "auto-dodge technique."
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