The long bell echoed throughout the school, signaling the end of the lunch break. The hallway and field, once noisy, gradually quieted down as students returned to their respective classrooms, small conversations still lingering in the air.
Raku walked back to the classroom with Shu, Ruri, Onodera, Chitoge, and Iroha.
As soon as the classroom door opened, students had already begun sitting at their desks. The atmosphere was slightly noisy, some yawning after lunch, while others were still busy chatting with their seatmates.
Raku entered calmly, then sat at his desk near the window. His gaze paused for a moment, watching the afternoon sunlight streaming through the window glass, casting a warm hue into the classroom. His heart felt calm, though in the corner of his mind, questions about the faint flash he experienced earlier this morning still lingered.
Not long after, the classroom door opened again. Kyoko-sensei, the mathematics teacher and their homeroom teacher, stepped in carrying a stack of books in her hands.
"Alright, everyone, return to your seats. Let's begin the next lesson," Kyoko-sensei said in a firm yet gentle voice.
The small commotion immediately subsided. The students sat upright, though some still struggled to stay awake. Shu leaned toward his desk and whispered softly to Ruri, "After lunch and then math… the deadliest combination."
Ruri lightly punched her arm. "Don't be lazy. If you don't study, it'll get worse."
Kyoko-sensei wrote on the blackboard with white chalk, numbers and symbols covering the board's surface. "Today we will discuss quadratic functions. This concept will appear in various problems, so pay close attention."
Raku took out his book and began taking notes neatly. His hand moved quickly, following Kyoko's explanations. Though his face remained expressionless, his eyes observed every detail as if he were truly absorbing everything.
Some students around glanced at him. A few whispered softly.
"Eh, didn't he just come back to school?"
"They said he has amnesia, right? How come he's writing so easily?"
Raku faintly heard the whispers but didn't respond. He simply continued focusing, staring at the problems Kyoko-sensei wrote on the board.
Kyoko-sensei turned to face the class. "Alright, now let's try some practice problems. For example, determine the maximum value of this quadratic function…" she wrote the equation on the board.
The classroom fell silent again. The sound of pencils scratching on paper filled the room. Some students looked confused, scratching their heads. Shu had already leaned back in his chair with a desperate expression. "Ugh, whose brain food is this? Not for me."
Ruri snorted. "Don't give up before trying."
On the other side, Raku had already finished writing his answer. He glanced at the problem for a moment, as if the steps flowed naturally, without any significant difficulty.
Kyoko-sensei walked between the rows of desks, her eyes briefly glancing at the students' answers. When she reached Raku's desk, she stopped, then gave a slight smile. "You finished very quickly, Raku."
Raku looked up and nodded gently. "I don't know why, it's as if the answer just appeared in my mind."
Kyoko-sensei nodded. "That's good. Don't hesitate to keep learning, even if it feels easy. Knowledge is not just memorized, but also understood."
The class continued. Numbers, symbols, and graphs filled the blackboard. Kyoko-sensei's firm voice emphasized important points.
However, in the middle of the lesson, Raku's mind wandered again. He stared at the parabolic function scribbles on the board, but what appeared in his memory were reflections of energy waves, much more complex formulas, as if science and something larger were intertwined.
He gripped his pencil tighter. "Why do I always see things like this whenever a lesson begins?" he thought, without looking away from the board.
Time seemed to move slowly. The sound of chalk scraping the board mixed with the students' sighs as they struggled against drowsiness and confusion. Quadratic equations, discriminants, parabola vertices—all lined up neatly on the board.
Raku remained calm. His pencil danced across the paper, copying the solution steps quickly. There was no sign of hesitation on his face, as if each number and symbol were merely puzzle pieces he already knew how to assemble.
At the back, Shu had completely given up. His head rested on the desk, only occasionally lifting it to ensure Kyoko-sensei wasn't watching him. Ruri, sitting beside him, glared sharply, forcing Shu to hurriedly continue copying notes carelessly.
Kyoko-sensei finally put the chalk in the tray and clapped her hands, flicking off the white dust. "Alright, that's enough for today. Make sure to review these notes at home. Next week, we'll continue with application problems of quadratic functions. Don't fall behind."
Soft complaints echoed from some corners of the classroom. Some sighed quietly, others slammed their books shut, relieved that the lesson was finally over.
Kyoko-sensei smiled faintly, then gathered some students' notebooks on the front desk. "I will check your homework. Don't forget to complete it seriously."
She glanced briefly at Raku before leaving. "Raku, it seems you won't have difficulty with this material. But don't be too quickly satisfied. Keep sharpening your abilities."
Raku bowed respectfully. "Yes, Kyoko-sensei."
Kyoko-sensei left the classroom with graceful steps. Once the door closed, the atmosphere immediately erupted. Students' chatter resumed, some stood to stretch, others exhaled in relief as if escaping a tough exam.
"Fiuhhh… finally done," Shu said, dramatically collapsing into his chair. "I almost lost my life just now."
Ruri immediately scoffed. "What life? You weren't even paying attention. Fool."
Shu winced but didn't argue.
Raku simply sat silently, staring out the window. The evening sky began to turn red, white clouds slowly shifting to golden hues. His gaze was empty, but his mind full. The math equations on the board mingled with faint shadows—about energy, laws of physics, and… battles against something he himself had yet to understand.
Onodera turned in her seat, watching Raku who remained silent. She wanted to speak to him but hesitated, her fingers gripping her pencil tightly. Chitoge also glanced briefly, then quickly turned her face away, blushing for some reason.
The atmosphere of Sobu class gradually returned to normal, the typical school bustle filling the air again, yet in Raku's mind… everything still felt strange.