The double doors swung open, revealing the examination chamber. It was a functional space, dominated by a large, crescent-shaped table where the three Dasturs sat, their expressions a mix of scholarly boredom and mild curiosity. Behind them, a large blackboard was mounted on the wall, pristine and waiting. In the center of the room stood a pedestal housing a complex array of lenses and crystals—a projection unit connected to the Akasha System.
Ren walked to the center, his steps echoing slightly on the polished stone floor. Ningguang and Lisa took their seats in the designated observation area to the side, their presence a silent, supportive weight. The scholar who had escorted them stood near the door, slate in hand, acting as the proctor.
"Applicant Ren of Liyue," the central Dastur, a man from Ksharewar with thick spectacles, announced. "You may begin your presentation for the 'Elemental Thermal Regulation Unit' and the 'Cryo-Stasis Preservation Unit.' Please utilize the projection array."
Ren approached the pedestal. He placed his finalized schematic for the heater onto the scanning plate. With a soft hum, the Akasha interface engaged. A beam of light shot upwards, and a perfect, three-dimensional, rotating hologram of the heater materialized in the air above him. It was translucent, glowing with a soft green light, every wire and screw rendered in meticulous detail.
"This is the heater," Ren began, his voice clear and projecting well in the acoustic chamber. He gestured, and the hologram responded to his intent, expanding. "Its core function is the conversion of raw Electro energy into thermal energy through resistive heating."
He walked them through the design with practiced ease. With a flick of his hand, the hologram disassembled itself, the components floating apart like an exploded diagram.
"The power source is a standard Electro crystal," he explained, pointing to the glowing representation of the battery slot. "The energy flows through these insulated conduits—forged from a silver-iron alloy treated with alchemical agents to maximize durability—and enters the heating coil here."
He zoomed in on the coil. "The coil is the heart. By forcing the current through a high-resistance path, we generate heat. The key innovation is the regulator dial." He demonstrated on the hologram, turning a virtual knob. The contact point on the coil moved. "By altering the length of the active circuit, we control the resistance, and thus, the heat output. It allows for precise temperature control, unlike a simple fire."
He then moved on to the refrigerator, explaining the inverse principle: using a Cryo crystal and a heat-exchange lattice to draw warmth out of an insulated chamber, creating a stable, cold environment for preservation. He detailed the ceramic composite insulation, the safety seals, and the fan systems that ensured even distribution of air.
The Dasturs listened, taking notes. Their initial boredom faded, replaced by genuine engagement. The engineering was sound. Elegant, even. There were no wasted parts, no extraneous flourishes. It was a machine built with purpose.
"The design is… competent," the Spantamad Dastur, a woman with sharp features, admitted, adjusting her robes. "The energy flow is stable. The safety shut-offs are prudent."
"However," the Ksharewar Dastur interjected, leaning forward, "we must address the matter of efficiency and methodology. The core concept—heating and cooling—is hardly novel. Fontaine utilizes Pneumousia reactions for industrial thermal regulation. Natlan harnesses liquid Phlogiston for immense heat generation. Even here in Sumeru, we can achieve similar thermal effects by manipulating localized environmental data through the Akasha."
He gestured dismissively at the hologram. "Why regress to such… rudimentary fuel sources? Electro crystals are common, yes, but their energy density is low compared to these advanced alternatives. Why build a device that relies on digging rocks out of the ground when we have access to superior, nation-specific technologies?"
Ren nodded, anticipating the question. It was the classic scholar's trap: equating complexity with superiority.
"You are correct, esteemed Dastur," Ren replied respectfully. "If my goal were simply to create the most powerful heater possible, or the most efficient cooling unit for a laboratory, I would have made different choices. If this device were intended solely for Liyue, my Master, Cloud Retainer, could have easily incorporated adeptal sigils that draw power directly from the ley lines, achieving an efficiency that no crystal could match."
He paused, looking at each of the judges in turn.
"But that was not the goal. The goal was universality. And accessibility."
He gestured to the hologram, bringing the components back together into a whole, simple box.
"A device powered by Pneumousia works brilliantly in Fontaine, where the energy is abundant and the infrastructure supports it. But take that device to Mondstadt, and it becomes a paperweight. A heater reliant on Natlan's Phlogiston is useless without a supply line of volatile magma. And an Akasha-based thermal unit?"
He looked directly at the Spantamad Dastur. "It is a marvel of Dendro engineering, certainly. But it requires connection to the Akasha System. It works here, in Sumeru City. But does it work across the ocean in Inazuma? Does it work for a farmer in Liyue who is not connected to the Akasha tech?"
He shook his head. "My goal was to create a device for humans. Not for citizens of a specific nation, not for scholars with access to specialized grids. But for anyone. Electro crystals and Cryo crystals… they are found everywhere in Teyvat. The materials for the coil and the casing are iron and wood, resources available in every village."
His voice grew firmer, filled with the conviction of his philosophy. "This device is not 'rudimentary.' It is independent. It does not rely on a god's specific blessing or a nation's unique resource monopoly. A blacksmith in Mondstadt can repair it. A merchant in Inazuma can power it. It is a universal tool, designed to bring comfort to everyone, regardless of where they live or what god they worship."
The room fell silent. The Dasturs exchanged glances. The boy had taken their critique of his "simple" technology and turned it into his strongest argument. He wasn't building for the ivory tower; he was building for the world.
"Universality," the Spantamad Dastur murmured, writing the word down on her slate. "An… intriguing design philosophy. And technically sound."
The Ksharewar Dastur cleared his throat. "Well. Yes. The point is… taken. However, there are still matters of long-term material degradation to consider. You mention a silver-iron alloy for the wiring. Under constant thermal stress, even treated alloys are prone to oxidation and brittleness over time. How do you account for the longevity of the heating element without periodic, high-level maintenance?"
Ren smiled. He was ready for this.
"That," he said, tapping a specific section of the hologram, "brings us to the alchemical treatment of the insulation layer…"
The review continued, diving deeper into the technical specifics, but the atmosphere had shifted. Ren wasn't just a child presenting a toy; he was an engineer defending a philosophy. And he was winning.