"I should probably find some biology books to read!"
After conducting a few basic experiments on common insects like ants and caterpillars, Roy came to a very inconclusive conclusion:
His body modification ability was extremely powerful—absurdly so.
Using this power, Roy strengthened an ant's body, greatly enhancing its limb strength and outer shell toughness, making it capable of lifting an entire caterpillar with ease.
And after experimenting on the caterpillar, he mutated its prolegs and thoracic legs into something resembling those of a centipede—clearly a genetically modified organism now.
Muscles, bones, internal organs, even electronic signals, cell activity, and genetic spirals—all were laid bare before his eyes.
But Roy couldn't perform precise modifications.
His modifications to the ant and the caterpillar had essentially been done with brute force; even he didn't know exactly how he'd done it.
That was because Tiamat's ability was just too complex—too versatile. It encompassed physical restructuring, ecological fusion, individual replication, and even manipulation at the cellular and genetic level.
Put simply, everything about carbon-based life was within her authority.
What Roy had received was nominally "Body Modification," but in truth, it was a stream of power trickling down from Tiamat herself—so naturally, it included aspects of her entire scope.
Whatever Tiamat could do, so could he.
Only—his version was a drastically nerfed one.
And the more abilities he had, the harder they were to control. Mastery would require extensive experimentation and time before he could wield them with finesse.
Most crucially, he needed a deep understanding of everything in carbon-based organisms—from body systems down to genes and cells.
In simple terms: the more knowledge he gained, the more powerful the ability would become.
Among all possible modifications, the easiest to alter were tissue strength and physical traits. That much was certain.
Tissue strength included things like muscle density, bone hardness, and even skin texture.
Physical traits meant characteristics like arm length, number of limbs, and so on.
"Rin, do you know where I could find some comprehensive biology books?"
"Biology books?"
Rin looked at Roy with a confused expression.
You're out here exploring a whole new world, and you're… looking for biology books?
"I remember there's a library in the city hall. They've got a lot of books from before the Great Calamity. You might want to check there."
"Got it!"
"Dinner's almost ready, so don't take too long."
"Okay."
Roy quickly changed into his outdoor clothes and headed straight for city hall.
There were still a few staff working overtime, and with his Magus rank insignia, Roy was easily allowed into the library. After a bit of searching, he found several books on biology.
***
Aozaki Mansion.
As Roy walked out the door, Hayasaka watched him leave, then turned her meaningful gaze toward Rin.
She stared at Rin for a moment before suddenly speaking, startling her.
"Lady Rin, are you planning to visit Lord Roy's bedroom tonight?"
"Hayasaka! Have you no shame?!"
Rin practically exploded, her twin tails standing on end like a startled cat. Her face turned beet red as she glared at Hayasaka with embarrassment and indignation.
Hayasaka sighed, looking at Rin with a mix of disappointment and pity.
"So you're not planning to go tonight?"
"T-That's… I have my own methods! You don't need to butt in!"
Rin averted her eyes and shot Hayasaka a faux-angry glare, then turned to pour oil into the pot.
"Wait—!"
Hayasaka quickly noticed there was still a shallow layer of water in the pot and tried to stop her.
"It's hot!"
Before she could finish her sentence, oil splashed from the pot, and Rin recoiled in pain.
"Honestly… guess there's no helping it."
Watching Rin retreat from the stove in a flustered panic, Hayasaka let out a deep sigh. Her expression firmed, as if she'd made a decision.
At Dinner.
Aoko had already left. According to the other girls, she'd departed Fuyuki City. Touko remained her usual elusive self.
Roy didn't pay it much mind, reading his biology books even as he ate.
Despite being a magus, Roy's knowledge of biology was fairly average—especially since he'd discarded what little he'd learned in his previous, mundane life. Touko probably had a deep understanding of the human body, but Roy desperately needed to brush up on the basics.
He was only looking for aspects of human physiology that would help bridge the gap in his own body. It didn't take long to read through the relevant parts—though if the internet worked in this world, he could've found all this in ten minutes.
"Hm. Rin, give me your hand."
"M-My hand?! What are you planning?!"
Startled, Rin almost shrank into herself, face flushed and eyes full of bashful protest.
"Why are you overreacting?"
Roy gave her a baffled look.
"I'm just checking your body. Hurry up."
"Geez…"
Pouting, Rin seemed both relieved and a little annoyed, but still obediently held out her hand.
Roy took her hand in his, noting the faint tremor.
He ignored her reaction and focused his perception on her body's internal structure.
"Damn… that muscle density!"
As he scanned Rin's organs and tissues, Roy couldn't help but be impressed.
Despite being a girl, Rin's muscle density was nearly twice his own!
Granted, Roy was a homunculus, and his body wasn't exactly peak performance… but even so, the gap was too big. No normal girl would have muscle density like this, right?
"I see. It really helps to have a baseline to compare to."
Roy nodded to himself in understanding.
Trying to follow Tiamat's body modification techniques to the letter would just make things more complicated. Who knew how long it'd take to master them?
The easier path was to find a solid sample and modify his own body to match it.
For example, if a hyper-fit version of Roy stood before him, he could scan it, copy the physical data, and transform himself accordingly.
Unfortunately, he didn't have a suitable sample right now.
As night fell completely, the mansion became quiet. With little in the way of entertainment in this era, Rin and the others retired early.
But Roy, having napped so well during the day, wasn't tired at all.
He headed down to the basement—his magus workshop.
Inside were numerous homunculi crafted by Touko. Most of them looked identical to Roy, giving the place a horror-movie vibe.
They had no souls—but that made them ideal for experimentation.
"Let's try muscle density first."
Placing his hand on one of the dolls, Roy recalled the data he'd gathered from Rin and carefully injected magical energy to begin the transformation.
Before long—
Roy opened his eyes.
"...Damn."
In front of him was another Rin.
Not just muscle density—even the hair, skin, and facial features were indistinguishable.
He glanced downward.
Good grief, even those parts had been completely altered!
If he ever went broke, he could just go to Thailand.
Way better than any "painless" operation.
It was only because this was his first attempt—and his lack of finesse—that this doll only resembled Rin by about 30 to 40 percent. With better technique, it could pass for the real deal.
"Yeah, I really need to develop more delicate control… and use each ability separately…"
Roy placed his hand on another doll, recorded its original structure, and began attempting to revert the transformed one back to its base form.
After several hours of trial and error, he finally began to grasp the trick.
Placing his hand back on the first doll, he channeled magical energy into it, making precise adjustments with painstaking care.
Before long—
A doll identical to Roy appeared before him—only healthier, and significantly stronger.
***
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