The sky that afternoon was the color of watered-down ink. Rain drizzled quietly against my window, the kind that made you want to do nothing but watch droplets slide down the glass. I had just settled with a cup of instant coffee when my phone buzzed on the desk.
Himari-san: "Observation Phase Resumed. Prepare Tea."
No greeting. No warning. Just like always.
I glanced out at the rain again. If this were any other person, I would have ignored the message. But this was Himari-san—an unpredictable force of nature wrapped in a lab coat.
Fifteen minutes later, the sound of the doorbell mixed with the soft patter of rain. When I opened the door, there she was, hair slightly damp, white shirt tucked into her skirt, holding a transparent umbrella like it was a scientific instrument.
"You didn't specify whether it was green tea or black," I said.
"I wanted to see which you would prepare," she replied calmly, stepping inside. "Your decision-making under uncertain conditions is part of the observation."
There was something off, though. Her usual spark was dimmer. She looked… tired.
"You okay?" I asked, pouring hot water into the teapot.
"Define 'okay,'" she said, sitting down at the small dining table. "I conducted three experiments this morning. Two failed. One exploded."
"That last one sounds pretty okay, considering you're still alive."
She gave a soft snort. That counted as laughter in Himari terms.
I set the cup in front of her. The rain outside thickened, blurring the city into streaks of gray and silver. For a while, we just sat there, sipping tea.
"You didn't text me for three days," I said quietly. "I was starting to think the experiment ended."
She stared at her cup, not at me. "It didn't end. I just needed time to process… variables."
"Variables?"
Her eyes flicked up to meet mine. "Human emotion is unpredictable. Difficult to quantify. It complicates results."
Ah. So we were back to that. Her safe words. But her hands trembled slightly as she held the cup.
"I see," I said. "So your hypothesis about the 'affective response during shared meals' is inconclusive?"
She bit her lip. "You're mocking me."
"Only a little."
Another silence stretched between us, filled by the soft rhythm of rain.
Then, suddenly, she stood. "Let's test something else."
Before I could ask, she walked toward the balcony. The rain was heavier now, a silver curtain outside. She slid the glass door open and stepped out barefoot.
"Himari-san—hey!"
Too late. She tilted her head up toward the clouds, letting the rain soak her hair and shirt.
"Data collection!" she called, half-laughing, half-yelling over the sound of rain. "I want to know how long it takes for body heat to drop under mild precipitation!"
I sighed and stepped out after her. The tiles were slick underfoot, and the air smelled of wet earth.
"You're going to catch a cold," I said.
"That's data too."
"You're unbelievable."
She smiled then—an unguarded, genuine smile that didn't look like an experiment. Her dark hair clung to her cheeks, eyes bright even through the rain. For a moment, the world narrowed to just her.
Something inside me cracked quietly, like the first sound before thunder.
I stepped closer, holding my umbrella over her. "You're ruining the results."
"I don't mind," she said softly. "Maybe some results are meant to be ruined."
Her voice was barely audible under the rain, but it was enough.
We stood there for a while, sharing the small circle of dryness under the umbrella. Water dripped from her sleeves, down to her fingers. Without thinking, I brushed a droplet away from her wrist. She didn't move.
"Do you always let your test subjects this close?" I asked.
"Only the persistent ones," she murmured.
It was absurdly quiet then. Only the rain, the faint hum of the city below, and the pulse in my chest.
After a moment, she stepped back and adjusted her hair, as if sealing away that brief vulnerability. "Experiment complete. I have my data."
"Sure you do," I said. "And what does it say?"
"That I should avoid future exposure to irrational subjects."
I smiled. "So I'm the irrational one now?"
She gave a tiny nod. "You skewed my results."
Inside, we both changed into dry clothes—well, I handed her one of my hoodies, which nearly swallowed her whole. She didn't complain, just curled up on the couch, knees drawn to her chest.
The air between us had shifted. Softer now, like the silence that follows a confession neither of us had voiced.
"Do you ever stop analyzing?" I asked after a while.
She rested her chin on her knees. "Only when I'm with you. Then it's… harder to think."
That was the first time she admitted something without hiding behind scientific terms.
I didn't reply. I didn't need to.
The rain kept falling, steady and constant, like a soundtrack to something quietly blooming.
After an hour, she stood to leave. "Observation will resume later," she said, avoiding my eyes. "I'll process today's data."
"Right. Let me know your findings."
At the door, she paused. "Hoshino-kun."
"Yeah?"
Her fingers lingered on the doorknob. "If emotions were measurable… I think I'd be afraid to see the results."
She left before I could answer.
The door clicked softly behind her. Outside, the rain eased into a drizzle.
I looked at the umbrella still leaning against the balcony door and laughed quietly.
Maybe some experiments weren't meant to be completed. Maybe the beauty of it all was in the uncertainty—the sweet, frustrating, impossible summer between two people who refused to name what was happening.