In the classroom of Class 1, Grade 10, there were still thirty minutes left before the end of second period.
The math teacher was drawing function graphs on the podium, the chalk and blackboard rubbing together in a steady, scratchy rhythm.
The dark green board was completely filled, x-axis, y-axis, parabolas, white lines layered one on top of another, like a web woven tighter and tighter.
The math teacher was a middle-aged man with a slightly receding hairline. When he taught, he liked to tap the board with the chalk.
Each tap sent fine white dust springing from the point of impact, floating in a small puff of mist in the sunlight streaming through the window.
It was a June morning, the air thick and muggy.
The three-blade ceiling fan turned lazily overhead, a thin layer of dust clinging to the edges of its blades. Every rotation it let out a creaking… like an old groan, as if it might fall off at any moment.
The air it stirred carried a warm, stale smell, brushing against the people below as if it hadn’t moved at all, at most lifting a few strands of hair from the students in the front row before letting them flop back down limply.
All thirty-plus students in the class felt as if they had been stuffed into a half-open steamer, each enduring the same sticky heat in their own way.
Some used textbooks as fans, pages flipping noisily, but the air they stirred was all hot.
Some rolled their sleeves up past their elbows, revealing arms that pressed red marks into the desks.
Some simply lay their heads on the tables, cheeks against the slightly cool surface, trying to steal a trace of coolness from the wood.
The curtain by the window was half-drawn, the off-white fabric puffing out slightly and then sagging with the hot breeze, as if breathing slowly.
But Shirase Rinna, sitting in the last row by the window, was resting her chin on her hand, quietly gazing outside.
She wore a black winter uniform jacket, zipped up to her collarbone, revealing the collar of a white shirt underneath, the top button fastened neatly.
A black uniform skirt just above her knees, her slender legs wrapped in black stockings so thin they looked like a second layer of skin, faintly revealing the fair skin beneath.
The heels of her black leather shoes rested lightly on the crossbar under the desk. From head to toe, she was bundled up tightly.
In June, wearing that outfit, she was not hot.
Her constitution was different from normal people—she was extremely sensitive to cold. To her, the June temperature was at most “not cold anymore.”
She had no abnormal sweat glands; it was simply a weak constitution, a metabolism so slow it was like a heater turned to the lowest setting, never producing heat fast enough to keep up with loss.
Her skin was cool all year round, like a piece of jade just pulled from well water.
While others were sweating profusely, her forehead didn’t even show a trace of moisture.
“Ice skin jade bones, naturally cool without sweat.” When Rinna had read that phrase in a book before, she thought it was literary exaggeration. Now she had become a living example of it.
But the price was wearing winter clothes in summer.
***
In the June classroom, her outfit stood out starkly from everyone around her.
Kikyo, sitting in front, was wearing a short-sleeved shirt, a few strands of hair stuck to the back of her neck with sweat, occasionally fanning herself with her hand.
The boy diagonally opposite had taken off his uniform jacket and hung it on the back of his chair, sleeves rolled up high, a thin sheen of sweat visible on his arms.
Rinna, however, was like a winter creature mistakenly placed in summer, quietly staying in her own corner, like a shade-loving plant that didn’t need much sunlight.
This corner—the seat in the last row by the window in Class 1, Grade 10—was privately called the “King’s Throne” by the classmates.
Not because Rinna wanted to sit there.
In fact, with her frail constitution that left her breathless after two steps, she didn’t even have the autonomy to “choose where to sit.”
When the homeroom teacher was arranging the seating chart, Hisaki went directly to the Academic Affairs Office and, on the grounds that “Rinna is physically unwell and not suited to inhaling chalk dust,” had her seat moved to the last row by the window.
Chalk dust.
The reason sounded far-fetched, but Hisaki had said it with a straight face, and it actually made some sense.
Rinna turned her head and glanced toward the podium.
The teacher was writing furiously at the blackboard, chalk tapping tap tap tap against the surface. With every stroke, fine white dust fell from the contact point between chalk and board, floating in small puffs in the morning light.
The students in the front rows, especially those right in the middle of the first row, seemed to have a visible layer of white dust hovering over their heads.
The chalk dust settled on their textbooks, hair, and shoulders, like a very fine, very light snow.
Over time, even the edges of the books took on a permanent white stain.
When Rinna used to sit in the front, she would cough for half an hour after every math class, her throat feeling stuffed with cotton, unable to cough it out or swallow it down.
So Hisaki’s reasoning, when you thought about it, was actually valid.
But Rinna knew in her heart that this was only the first reason.
The second reason, Hisaki had never told anyone, but Rinna knew.
It was June.
Summer.
The girls sitting in the front, especially those in summer uniforms with only a thin bra underneath, when they got hot and sweaty, the backs of their shirts would easily become damp, revealing the outline and color of their undergarments.
Light-colored shirts were especially noticeable; when wet, they were almost transparent.
The boys might not stare deliberately, but “not deliberately” and “absolutely not notice” were two different things.
The girls in the class all tacitly understood this. Those with experience would wear an extra undershirt on hot days, or choose dark-colored bras, or simply use their backpacks to cover their backs.
But oversights were inevitable.
Hisaki thought that was unacceptable.
To be precise, Hisaki believed that “the possibility of anyone seeing Rinna’s bra outline” was itself unacceptable.
Even if the probability was one in a thousand, even if Rinna herself never sweated, even if her winter uniform was thick enough to never show anything.
Hisaki still wasn’t at ease.
Her logic was simple: if sitting in front carried this risk, then sit in the back.
Sit in the last row, and no one in front can see your back.
Sit by the window, and the only things next to you are the window and curtain, blocking most of the view from the neighboring desk.
So Rinna now sat there.
Last row, by the window.
Sometimes Rinna thought Hisaki’s overthinking was kind of endearing.