The next morning, Jin hurried through breakfast and immediately set to work on the new Body Double.
"Creating an automaton with all five senses isn't that difficult."
He began with the basic premise.
Standing before Jin were Reiko, Elsa, Anne, Loll, and Refa. Laojun was also participating in the discussion, of course.
"The real challenge lies in sensory sharing and body control."
Jin began to explain why this was so difficult.
"If my sensory feedback is capped at a low limit, yet the control commands I send out are unrestricted, we run into a contradiction."
"My Lord, what do you mean by that?" Anne asked.
Jin felt his previous explanation had been a bit obtuse, so he tried to rephrase his thoughts.
"I’m not a hundred percent confident in the theory myself... but in order to exert force, you need to know exactly how much power you're putting out and how that power is affecting the target."
"I understand that," Reiko said, nodding deeply as she recalled the moment she first gained her tactile sense.
"But for someone like me, there was no hindrance to my movements even without a tactile sense..." Anne noted wonderingly. The reason for that was simple.
Automata and golems like Anne and Reiko possessed such extreme reaction speeds that they could perceive an object's behavior and adjust their strength accordingly even without a sense of touch. For instance, when lifting something, they would start with a negligible amount of force, detect that the object wasn't moving, and then gradually increase the output. They were capable of performing this entire calculation in less than a tenth of a second.
If they didn't do this and simply used full power from the start, disaster would strike. It would be like lifting something heavy only to realize it was actually light—the excess force would cause them to flip over, send the object flying, or accidentally crush it.
"It's a difficult balance..."
"Oh, then what if you lowered the sensitivity in proportion to the power output?" Loll suggested.
Jin was struck by the proposal.
"..."
"Um, My Lord? Did I say something wrong?" Loll asked, her expression growing anxious at his silence.
Jin quickly shook his head. "Ah, no, not at all. On the contrary, it’s such a good idea that I was just processing it."
Increasing a value from one to two wasn't the same as increasing it from 1,001 to 1,002. That was the essence of her idea.
Deciding it was well worth a try, Jin set to work.
＊ ＊ ＊
Building the body was a task Jin had repeated so many times he could practically do it with his eyes closed.
"I'll set the strength limit to the power of about ten men."
Any more than that and Jin would likely find it impossible to control.
"Instead, I'll add more specialized modes."
For vision, he made it possible to switch between normal mode, telescopic mode, and night vision mode. For hearing, he included an ultrasonic mode, though he kept the default set to the standard audible range. Being able to hear into the ultrasonic range all the time would surely be more annoying than helpful.
"Finally, the Magilink."
By deepening this connection, it should make Jin feel as though he had truly possessed the machine.
The control device on Jin's end was designed as a helmet to be worn over the head. The operator would wear the helmet while lying back in a comfortable, reclining seat.
"Jin-nii, are you sure about this?" Elsa asked, looking worried.
"Yeah. I'll start the synchronization rate at a low level, so it’ll be fine. If for some reason I don't respond when you call out to me, just cut the mana to the control device."
"...Okay."
"Alright, let's begin the test."
Jin lay down in the seat and donned the controller.
Since the exterior plating hadn't been attached yet, Jin's new Body Double looked more like a golem than an automaton. It slowly sat up. Then, just as it seemed it had begun to take a few awkward steps, it came to a Stand Still.
"Hmm, this isn't right."
Removing the control device, Jin made some adjustments. Then he experimented again. The movements were still clumsy. He adjusted it once more.
After three rounds of fine-tuning, the movements finally became fluid.
"Oh, this time is much better."
The words finally came from the Body Double's mouth. The voice sounded a bit distorted, but it was functional.
"Just a little more."
Jin performed two more adjustments.
"Yes! It moves exactly how I want it to."
The Body Double ran a short distance and hopped in place.
"Alright, let's try it outside."
Jin walked the Body Double out of the laboratory. Reiko and Elsa followed him, while Anne, Loll, and Refa remained in the workshop.
Stepping out into the laboratory's front yard, the Body Double performed full sprints and high leaps.
"Amazing," Elsa whispered. It was only natural for her to be impressed; the unit was sprinting at speeds far beyond any human capability. Its jumps reached nearly five meters in height.
"Well, this should do. Reiko, give me a hand with a sparring test."
"Yes, Father."
Jin intended to try some simulated combat with Reiko.
"Here I come!"
The Body Double closed the distance in an instant, thrusting out a fist with blinding speed. Reiko calmly parried the strike. Fists flew in rapid succession, punctuated by the occasional kick, but Reiko dodged and blocked every one of them.
"Alright, that's excellent."
The Body Double stepped back to create some distance. The body's specs were high, but Jin's own combat skill was the bottleneck; this seemed to be the limit of what he could manage.
"Reiko, for now, let's do one last test. Punch me with two percent of your strength."
"What? But that's..."
"Jin-nii, are you sure?"
Reiko hesitated and Elsa looked on with concern.
"Yeah. I have to test the durability eventually. At two percent of Reiko's strength, it shouldn't break. Please."
"...I understand. Here I come!"
Steeling her resolve, Reiko stepped in and threw a punch.
With a dull metallic clang, the Body Double was sent flying about twenty meters.
"Father!"
"Jin-nii!"
Hearing the muffled groan Jin had let out the moment of impact, Reiko and Elsa went running toward the laboratory.
"Onee-sama, My Lord is fine," Anne said to reassure Reiko as she literally came flying into the room.
"Ah, Reiko. Sorry for worrying you. I'm okay."
"That voice just now...?"
"Yeah, getting punched really is unpleasant. It didn't actually hurt, but I let out a noise out of pure reflex."
"I see... that is a relief."
Elsa rushed in a moment later. Seeing Jin sitting up in the seat as if nothing had happened, she cried out.
"Jin-nii!"
She threw herself at him.
"W-Whoa, Elsa..."
"...I'm so glad you're safe."
Her voice was a little tearful; she must have been incredibly worried. Jin gently patted her on the back.
"It's a great success. I could feel the impact, but there wasn't any pain. With this, it can truly serve as my substitute."
After this, the new Body Double was given its final maintenance and its exterior plating was attached, making it look exactly like Jin. Further tests confirmed that its performance was almost exactly as desired.
While this new Body Double surpassed Jin in physical strength, there was one catch: regarding Craft Magic, it was only capable of performing at about the same level as a Smith Golem.
"Still, there probably won't be many situations where I'll need to use Craft Magic at full power while using this."
Jin gave the new Body Double a passing grade. And so, it was newly christened the "Doppel."