It was the kind of morning where the sun looked half-awake, struggling to push through the pale clouds. I was halfway through my second cup of coffee when I heard a knock on my door—three sharp taps, spaced evenly.
There was only one person in the world who knocked like that.
When I opened it, Himari-san stood there holding a paper bag in one hand and wearing an expression that could only be described as... defensive.
"I came to return this," she said.
My gray hoodie. Freshly washed, neatly folded, smelling faintly of detergent—and something softer underneath.
"You could've just brought it tomorrow during the experiment," I said, stepping aside to let her in.
She didn't move. "It was affecting my control group."
I blinked. "Your what?"
"My sleep cycle," she corrected quickly, stepping inside after all. "It was distracting."
"Right. Hoodies are known to interfere with REM sleep."
"I'm being serious, Hoshino-kun," she said, setting the hoodie on the table like it was radioactive. "You shouldn't lend personal belongings to test subjects. It creates—complications."
I smiled. "So you're saying I've contaminated your data."
She looked away. "Something like that."
The sunlight caught her hair, and for a moment, she didn't look like the calculated scientist who measured human reactions for fun. She looked… flustered. The faintest pink touched her ears.
"So," I said, trying not to sound too amused, "was it comfortable?"
Her eyes snapped toward me. "You're asking irrelevant questions again."
"Answering them is part of the observation."
"Fine," she muttered. "Yes. It was. Too comfortable. That's the problem."
That one line managed to silence me more effectively than any data chart ever could.
I watched as she unpacked her paper bag. Inside were two bentos, both neatly wrapped in patterned cloth. "Peace offering," she said. "To thank you for the tea and for not letting me catch hypothermia."
"Ah. The legendary Himari-san thanks. Rare species."
"I'm capable of gratitude," she said flatly, then hesitated. "Occasionally."
We sat at the table, eating in that strange mixture of quiet and warmth that had started to define our time together.
Her bento was, of course, perfectly balanced—rice, vegetables, grilled fish, all arranged with mathematical precision. Mine was… improvisational at best.
"Your cooking," I said between bites, "is so structured it could pass for a lab report."
"I measure ingredients by ratio," she said. "Precision ensures replicable results."
"And yet," I said, tasting the miso soup, "it somehow still tastes human."
Her chopsticks paused midair. Then she looked down, trying to hide the small smile that escaped.
"That's… a strange compliment," she said softly.
"Then it fits us perfectly."
She laughed once, under her breath. The sound was light, almost fragile, but real.
After lunch, she began organizing her notes again. That was normal. What wasn't normal was how she kept glancing toward the hoodie.
"You can keep it if you want," I said.
"I don't need it."
"Didn't say you needed it."
Her pen froze. "You're being unscientific again."
"Maybe that's the point."
She sighed—one of those slow, helpless sighs that said I was both annoying and impossible to ignore.
Then, without looking at me, she said, "I analyzed yesterday's data."
"Oh? What did you find?"
"That… prolonged proximity during rainfall appears to increase physiological response."
I leaned back in my chair. "You mean, your heart was beating faster."
She frowned. "I didn't say that."
"You implied it."
"I implied correlation, not causation."
"You're blushing."
"Side effect of caffeine."
"Liar."
She looked away, muttering something about "irreproducible anomalies."
The conversation died there, but the air between us was charged, like the calm before another experiment neither of us wanted to name.
Eventually, she stood to leave. But at the door, she paused again. "The hoodie—"
"Yes?"
"It… still smells like your apartment," she said, almost too quietly.
"That a complaint?"
Her lips curved in the faintest smile. "An observation."
And then she was gone, leaving me standing in the doorway with the soft scent of detergent and summer rain still hanging in the air.
---
Two days passed before she showed up again. I thought maybe she was avoiding me—but when I opened the door, she was holding a large notebook under her arm.
"I've been analyzing emotional responses," she said, walking in without waiting for an invitation. "There's an interesting pattern."
"Oh? Do tell."
"I noticed that since meeting you, my daily cortisol levels have fluctuated unpredictably."
"Sounds unhealthy."
"It's… not unpleasant," she admitted, flipping through her notebook. "But I can't identify the variable causing it."
I tried not to smile. "Maybe the variable isn't external."
She froze. "Meaning?"
"Maybe it's you."
For the first time, she had no comeback.
Silence filled the room, thick and electric. The ticking clock suddenly sounded too loud.
Then, softly, she said, "If I were to call this feeling something unscientific… it would ruin the purity of the study."
"Maybe some things aren't meant to stay pure," I said. "Maybe they're meant to get messy."
She looked up. Her eyes met mine, steady and uncertain all at once. "Then… would you continue observing with me?"
I smiled. "Always."
The sunlight slipped past the window then, scattering across the floor like a quiet promise. She reached for her pen, then hesitated, and instead—just this once—set it aside.
Outside, the last of the rain had dried, leaving behind that familiar fragrance of wet pavement and blooming summer air.
Inside, Himari-san leaned against the table, unguarded, quiet, and very human.
"New hypothesis," she said finally. "Emotions, once acknowledged, are irreversible."
"And your conclusion?" I asked.
She met my gaze, her voice barely above a whisper. "I think I'm okay with that."
And that was all it took. No dramatic gestures, no confession, no symbols. Just two people standing in the middle of a summer morning, realizing that whatever this was—it had already begun long before either of us tried to name it.
The fragrance of summer lingered, delicate and warm, like the trace of something beautiful we both pretended not to notice.