The droning cadence of Mr.Ishida's voice filled the Earth Science classroom. He stood before the blackboard, chalk dust clinging to his sleeve as he pointed to a diagram of the Solar System, currently fixed on Jupiter's swirling storms. Most students were sketching in their notebooks. Amami Sora, however, stared out the window, her gaze lost somewhere beyond the football field. Even the thought of planets, her lifelong passion, felt distant and tainted.
Mr.Ishida tapped the board.
"Alright class, quick review. Who can tell me why Pluto is no longer classified as a planet?"
He scanned the room, expecting a flurry of hesitant hands.
A hand rose in the middle row, firm and confident. It belonged to Kurosawa Haruki, a new transfer student who usually kept to himself, blending into the background. Sora blinked, surprised. She hadn't expected him to be the one.
"Yes, Kurosawa-kun?"
Haruki stood, his voice clear and articulate.
"Pluto doesn't meet the third criterion for planetary status. A celestial body must orbit the Sun, be nearly spherical, and have cleared its orbital neighborhood. Pluto hasn't cleared its orbit of other objects in the Kuiper Belt."
He paused, then added, almost as an afterthought.
"Though, it does make one wonder about the rigidity of our human classifications when applied to something as dynamic and vast as the universe. Do our definitions truly encompass the complexity, or do they merely simplify it to fit our understanding?"
Sora felt a jolt. How did he know all that in such precise detail? Most students would just blurt out "it's too small". And the philosophical twist? That was unexpected. A tiny flicker of interest, like a distant star, sparked within her.
Mr.Ishida cleared his throat, a hint of surprise in his expression.
"An excellent, comprehensive answer, Kurosawa-kun. And a thought-provoking addition."
He paused, then tried to regain control of the lesson.
But Haruki, still standing, wasn't quite finished.
"If I may, sensei, speaking of the outer Solar System, have you discussed 'Planet Nine'?"
A ripple of confusion swept through the class. Sora leaned forward, suddenly captivated. Planet Nine?
Mr.Ishida frowned slightly.
"Planet Nine, Kurosawa-kun? Do you mean the dwarf planet, perhaps Eris?"
Haruki shook his head.
"No, sensei. I'm referring to the hypothetical planet, estimated to be about five to ten times the mass of Earth, in the outer Solar System, far beyond Neptune. Its existence is inferred from the gravitational effects it has on highly eccentric orbits of distant Kuiper Belt objects. There's ongoing research, of course, but the statistical evidence is quite compelling."
The classroom fell silent. Mr.Ishida blinked, then rubbed the back of his neck.
"Ah, I see. My apologies, Kurosawa-kun. That's... a more advanced topic, still under active research. I confess, I wasn't aware of the specific details myself."
He looked genuinely flustered.
Sora stared at Haruki, her mind reeling. This wasn't just textbook stuff. He must have actively sought this out, researched it, gone way beyond what they were taught in class.
...
Mr.Ishida tapped a pen against his textbook.
"Alright. Your partner reported feeling unwell, so he's already left for the day."
Sora, who had been absently packing her bag, froze. This was it. An unexpected opportunity. Before Mr.Ishida could assign someone else, she blurted out, perhaps a little too eagerly.
"Sensei! I can help Kurosawa-san! My after-school club isn't meeting today."
Mr.Ishida looked mildly surprised by her sudden enthusiasm but nodded.
"Ah, Amami-san. Very commendable. Kurosawa-kun, Amami-san will assist you today."
Haruki turned, his expression unreadable, a flicker of something in his eyes that Sora couldn't quite decipher.
"Thank you, Amami-san."
His voice was quiet, polite.
As the last few students shuffled out, leaving behind the faint scent of chalk and stale air, Sora and Haruki began the mundane tasks. Sora took the damp cloth, wiping down the rows of desks, their surfaces cool and smooth under her palm. Haruki collected the trash, moving with an unhurried efficiency. The only sounds were the distant echoes of students' chatter from the hallways and the quiet squeak of the cloth against the laminate.
The silence stretched, not quite uncomfortable, but expectant. Sora's mind raced, trying to find the right way to phrase her question without sounding intrusive. Finally, as she reached his desk, she blurted it out.
"Kurosawa-san... about what you said earlier, about Planet Nine... how did you know so much about it?"
Haruki stopped, the small dustbin held motionless in his hand. He looked at her for a moment, his gaze analytical, as if gauging her sincerity. He glanced towards the open classroom door, a quick, almost subconscious check of the empty hallway, before turning his full attention back to her. A faint, almost wry smile touched his lips.
"Oh, that?"
He began, his voice a little quieter than before.
"I just... follow my curiosity. I find a question that interests me, like 'What's the weirdest thing about the outer Solar System?' and then I go exploring down the rabbit hole it creates."
He paused, a flicker of hesitation in his eyes. It was the kind of pause someone makes before sharing a secret or an unconventional method, testing the waters.
"My... study partner is a bit unusual."
He finally admitted, gesturing vaguely towards his pocket where his phone was.
"It's ChatGPT."
He said the name plainly, without fanfare, watching her reaction closely.
"It's an incredible learning assistant."
He added, his confidence returning as he elaborated on his philosophy.
"If you know how to use it for exploration, not just for answers."
Sora paused, the damp cloth still in her hand.
ChatGPT?
She'd used it for essays and summaries, but never like that. The way he'd revealed it with that slight hesitation, made it feel less like a simple tool and more like a carefully guarded secret to unlocking knowledge.
"Actually. One of the most fascinating hypotheses about Planet Nine, which ChatGPT led me to, is that it might not even be a planet at all."
He looked directly at her, his eyes bright with genuine curiosity.
"Some scientists propose it could be a primordial black hole. A very small one, roughly the size of a grapefruit, but with many times the mass of Earth, left over from the Big Bang."
Sora felt her jaw drop.
A primordial black hole?
That sounded like something straight out of a sci-fi movie, a fantastical concept, but he was saying it was a real, actual scientific hypothesis.
How did he even find out about these things?
Her mind reeled with the sheer depth and strangeness of this knowledge, so far beyond anything she'd encountered.
Haruki noticed her reaction, a faint smile playing on his lips.
"You seem really interested in space, Amami-san. It's not a common interest. What draws you to it?"
His tone was genuinely curious, without any hint of judgment.
Sora felt a familiar pull to confide in him, to share her lifelong dream, but the fragility of her dream, the futility of it in an AI-driven future, made the words catch in her throat. She couldn't say "I want to be an astronaut".
"Oh, it's just... I watch a lot of videos about it."
She said, her voice thin, avoiding his gaze as she resumed wiping a desk.
"Space is really interesting, isn't it?"
It was a weak, non-committal answer, and the sadness of holding back her true feelings was a bitter taste in her mouth.
Haruki didn't press. He simply nodded, then returned to stacking chairs. The quietness of the empty classroom settled around them once more, filled only with the soft sounds of cleanup, and the unspoken questions that lingered in the air.