The screeching sound of chalk on the blackboard echoed softly, occasionally mixed with the sound of Kyoko-sensei's footsteps pacing back and forth in front of the class.
"Alright, pay attention to this," she said, writing several formulas about energy and force. "Newton's Second Law: F = m × a. Force is mass multiplied by acceleration. From here, we can derive many things—velocity, momentum, kinetic energy."
However, most of the students began to look sleepy. Some propped their chins, some doodled in their books, and others stared blankly out the window.
Raku sat quietly in his seat, pen in hand but his eyes not fully focused on the blackboard. Something was strange. Kyoko-sensei's voice slowly began to echo, as if drifting far away. His vision blurred for a moment, then—
—a white light.
Suddenly he found himself standing on a beach. The sea breeze blew, the sound of waves crashed against the shore, and the evening sun reflected on the surface of the water. But the atmosphere wasn't normal—it felt like a memory, a fragment half-destroyed.
There, he saw a figure with black hair, faintly resembling someone he had seen before in a dream. That figure stood, gazing far into the horizon.
And beside him, a small creature appeared, shaped like a hologram—a chibi with a cute appearance, yet not an ordinary human. Its body was made of blue light, its eyes sparkled like data, and every movement produced transparent flashes like computer code.
The creature floated around Raku, its voice high-pitched yet clear:
"Physicsssss is important! Don't take it lightly. Look, Kinetic Energy is E = ½ m v², Potential Energy is m g h. That's basic. But you must remember: behind those simple numbers, there is a universal law that upholds reality."
Raku fell silent, his heart pounding. 'This… what is this? Why at the beach? Who are they?'
The hologram chibi kept spinning while waving its tiny hands.
"Your Arc of Embodimen… is not just a tool to create artifacts or magic. It works by following the laws of physics. You turn concepts into form, energy into tangible shape. But if you don't understand the basic laws of energy, you'll run out of power, even… be destroyed before fighting them."
The hologram light suddenly flickered, displaying images in the air. Shadows of a giant monster with a formless black body, Trihexa with six heads roaring from the darkness, the blurred silhouette of the Beast of Humanity from another world, and something even more terrifying—a colossal alien shadow from outer space that seemed to devour the very concept of light and time itself.
"Outer God, Trihexa 666, Beast of Humanity, Outer Space devourer of concepts… None of them are fairy tales. They are real, and to fight them, your understanding must go beyond merely 'I can create something'. Without physics, you can't even stand against them."
The little creature's voice grew more serious.
"Energy cannot be created or destroyed, only transformed. Remember the law of conservation of energy! If you create something without understanding the energy required, your body will collapse. If you don't know the limits of thermodynamics, the reality you form will crack. If you don't understand the law of entropy, your own power could become a black hole that swallows the world!"
Raku stared at the beach, his body trembling. Those words pierced his head, as if they were not merely theory. There was something behind those explanations—a warning.
"So… I have to learn physics… to survive?" he muttered softly.
The hologram chibi turned to him, its smile softening a little.
"More than that. To protect, to remember who you are, and to restore the shattered world. Your Arc of Embodimen is not a fantasy power—it is bound by the laws of reality. Understand physics, and you can defy them. Ignore it… and you will vanish before you can even fight."
Suddenly, the sound of cracking was heard. The sky of that beach broke like glass, fractures of light spreading rapidly.
Crack… crack…
Everything collapsed, and Raku was thrown back into his seat in the classroom.
"…and because of that, gravitational potential energy can be converted into kinetic energy when an object falls." Kyoko-sensei's voice returned clearly to his ears.
Raku jolted, his breath slightly heavy. He looked at the blackboard—the formulas appeared exactly as explained by the hologram chibi earlier. His hand trembled lightly as he held the pen.
'Just now… was that a dream? A memory? Or… a message from something else?'
He stared blankly at the desk, letting Kyoko-sensei's voice continue to echo. The other students had gone back to their habits—some lazily taking notes, some nearly asleep. But for Raku, every word "energy," "force," and "physics" now felt different.
In his heart he murmured:
'Physics… to fight Outer God? What am I, really?'
The chalk screeched again on the blackboard, forming a new equation. Kyoko-sensei glanced briefly at the students who were starting to lose focus, then spoke in a slightly firmer tone:
"Energy… never disappears. It only changes form. For example, when an object falls from a height, potential energy turns into kinetic energy. This simple concept is the foundation of everything you see around you—machines, electricity, even the human body."
The class remained silent, some students trying to take notes, others only staring blankly at the blackboard.
Raku sat still, the pen in his hand unmoving. Kyoko-sensei's words seemed layered with another echo—the voice of the hologram chibi that had appeared in his faint memory.
"Energy cannot be created or destroyed… without physics, you will vanish before you can fight them… Outer God…"
His mind spun. Outer God? Trihexa? Beast of Humanity? Those names were unfamiliar, yet they etched a fear he couldn't explain. As if his brain knew the words, but his body refused to remember.
His hand clenched slowly on the desk.
'Why me? Why do I have to think about things like this? I don't even know who I am… and why I lost my memories. If that's true, if I really once fought against something that big… how am I still alive now?'
His eyes glanced at the blackboard. Simple formulas—E = mc², F = m × a. Something taught as ordinary school lessons. But inside his heart, those formulas felt like the key to something far greater, something that could decide whether he would survive or be destroyed.
His chest felt tight. There was a strange pulse, like a heartbeat pounding not in his body, but in the depths of his soul.
"Outer God… Trihexa… who am I, really?" he whispered almost inaudibly.
The class continued as normal, Kyoko-sensei still writing on the board, the murmur of students whispering faintly audible. But for Raku, the world seemed layered—one layer of ordinary school life, and another that kept pulling him toward terrifying questions:
Was he truly just a high school student with amnesia?
Or… something more than that, something even the gods feared to name?
His gaze dropped to his notebook, the blank page staring back at him. The pen in his hand trembled before he finally wrote a single word with shaking hand:
"Who am I?"
The sentence stood out clearly, as if it was the core of all the unanswered questions.