2:08 AM — The Hour When Equations Smell Like Burnt Coffee
The Konbini smelled of academic defeat. Miyu, hunched over her notebook on her lap next to the vending machine, nibbled on a pen as if it were a Pocky. The exercise sheets were so full of cross-outs they looked like maps of bombed cities.
"Why does X always have to be a number?" she groaned, throwing the pencil at a box of Spicy Ramen. "Maybe X is a feeling! Or a typo!"
Aoi, sitting on the counter with old receipts, tossed them into the air like paper grenades.
"X is the unknown, like Hiroto-kun's minimum wage," she said, sticking a receipt onto the forehead of a promotional beer plushie. "Or the number of neurons he uses to breathe."
"Breathing uses the medulla oblongata, not neurons," I said without looking up from the inventory.
"There it is!" Aoi pointed at me with a receipt. "Thank you, Hiroto-sensei, expert in medullas and in pretending nothing matters."
Miyu looked at her equations as if expecting them to solve themselves by magic.
"I don't understand... Why do I have to solve for Y if I don't even know what it means?"
"Because that's how life is, Miyu-chan." Aoi jumped off the counter, dragging a chair toward Miyu. "You have a bunch of problems, you try to solve them, and in the end..." She paused. "...it doesn't matter! In 100 years, no one will remember your grades or that you were even alive."
Miyu dropped her head against the wall with a dull thud.
"I'm going to fail..."
"Show me," I said, closing the cash drawer and walking over.
Aoi raised an eyebrow.
"Mr. 'I Only Criticize Things' knows math?" she teased, though her smile had an edge of curiosity.
Ignoring her, I took Miyu's notebook. The problem was simple, too simple and specific: A Konbini sells 120 cans of coffee at 150 yen each. If the cost per can is 90 yen, what is the total profit? Miyu had written: 120 + 150 = 270 – 90 = 180 (?).
Who gives a middle school student a problem like that?
"Miyu..." I sighed. "This is wrong."
"I know!" she shouted, burying her face in her hands. "Math hates me!"
"No. Math doesn't care about you, like the universe," I said, dragging a chair next to her. "First, calculate the revenue: 120 cans × 150 yen."
"18,000 yen!" Aoi interjected, throwing a receipt that landed on Miyu's head. "And the cost is 120 × 90 = 10,800. Profit = 7,200! Easy."
We both looked at her.
"What?" She shrugged. "I did accounting in middle school... and besides, that problem looks like elementary school level."
Miyu looked at her calculations, then at Aoi's, and groaned again.
"See? Even she knows it..."
"Don't compare," I said, pointing at the problem. "You added 120 + 150. That's like mixing coffee with ramen."
"But they're both brown!"
She had a point.
"It's not the same," I lied, drawing a table in her notebook. "Imagine each can of coffee is an ofuda. You sell 120 ofudas at 150 yen..."
Aoi leaned in.
"You're really using ofudas to teach? That's dark."
"...and each ofuda costs you 90 yen," I continued, ignoring her. "How many ofudas worth of profit do you get for each ofuda sold?"
Miyu blinked, then smiled.
"60 yen! 150 - 90!"
"Exactly. Now, 120 ofudas × 60 =..."
"7,200!" Miyu shouted, drawing a giant ofuda in the margin. "I get it!"
Aoi watched in silence, biting a Pocky with more force than necessary.
"Well, that was weird," she said suddenly, swinging in her chair. "What's next? Practicing sports at a Shinto shrine?"
"Try this one," I passed another problem to Miyu. "If a customer buys 3 onigiri at 120 yen each and pays with a 1,000 yen bill, how much change should they get?"
"864 yen!" Aoi interjected again, throwing a plastic-wrapped onigiri toward Miyu. "Because 3 × 120 = 360. 1,000 - 360 = 640. Oh, wait! I was wrong."
"640," I corrected, pointing at the error. "Aoi, let her solve it."
"Yes, Hiroto-sensei~," she chirped, pulling her chair closer until her shoulder brushed mine. "Do you also give classes on how to be an insufferable know-it-all?"
Miyu solved the problem, this time without ofudas, but with a triumphant smile.
"640! I did it!"
"Good," I said, putting away her notebook. "Now, apply the same thing to equations. X isn't a feeling. It's a number in disguise."
Aoi yawned exaggeratedly.
"What if X is the number of times Hiroto-kun has smiled in his life?" she asked, drawing a heart around a problem. "X = 3, including when he tripped over the coffee machine."
"X = 4," I replied without thinking. "You were distracted the fourth time."
The silence that followed was so thick that even Miyu stopped writing. Aoi opened her mouth, closed it, then jumped out of her chair.
"Time to check the puddings!" she announced, marching toward the dessert fridge with the elegance of an embarrassed cat.
Miyu looked at me knowingly.
"I think Aoi-san is jealous."
"No. She just hates losing," I said, though I noticed Aoi hitting the fridge harder than necessary.
The rest of the night, Aoi interrupted every five minutes:
"Need help solving equations? I know how to clear... the aisles of drunk customers!"
"What if Y is a yokai? Y = 20 yen!"
"Look, Hiroto-sensei," Miyu whispered, pointing at a geometry problem. "How do I find the area of this triangle?"
"Base times height divided by two," I replied, drawing in her notebook.
Aoi appeared behind us, hanging off my shoulders like a living coat.
"The answer is love!" she sighed, exaggerating a faint. "Because love is a triangle... and everyone gets hurt."
"It's a right triangle, not a tragic one," I said, trying to ignore her strawberry gum breath.
At 4 AM, Miyu dozed off on her notebook, a volume formula written on her cheek. Aoi, reclining on the counter, tossed Skittles into an empty cup.
"I didn't know you were good with numbers," she murmured, not looking at me.
"That's why I'm in charge of counting the cash in the register," I replied, pointing at the counter.
"When was the fourth time?" she asked suddenly, staring at the ceiling.
"What?"
"The smile. The one I didn't see."
...
...
"When you put wasabi in the matcha ice cream."
She smiled, a genuine gesture that lasted less than a sigh.
"Idiot."
"You're one too."
Miyu snored softly, her cloak turned into a blanket. The Konbini lights flickered, and for the first time, the buzz sounded almost relaxing.
Aoi jumped off the counter, tossing me a Pocky that I caught mid-air.
"Tomorrow I'll teach you how to calculate the density of Doritos~," she said, disappearing behind the snack aisle.
And so, amidst numbers and stolen smiles, another night ended.
As always.