The orange glow of the Tokyo sunset had faded into a deep, bruised purple. Inside Room 404, the only light came from the glowing standby LED of the microwave and the soft blue hum of Ren's laptop.
Shizuka stood by the window, her arms wrapped around herself. The "Invisible Line" they had drawn earlier felt less like a boundary and more like a tightrope.
"I'll sleep on the floor," Ren said, his voice cutting through the silence. He didn't look up from his screen, but his fingers were moving slower over the keys than usual. "I'm used to pulling all-nighters anyway. A carpeted floor is an upgrade from a computer lab chair."
Shizuka looked at the floor—hard, thin industrial carpet over cold concrete. Then she looked at Ren. He was tall, and the idea of him curled up like a discarded coat made her chest tighten with a strange guilt.
"No," she said, her voice firmer than she felt. "I am the adult here. I am the Professor. It's my responsibility to ensure my... my roommate's well-being."
Ren finally looked up, a brow arched in amusement. "So you're pulling rank to get the floor? That's a new one, Professor."
"I'm saying," Shizuka stammered, her face flushing, "that the bed is a King-sized premium. It was designed for 'couples' or 'executive faculty.' It's... it's huge."
Ren stopped typing. The air in the room suddenly felt twice as thick. "Are you suggesting what I think you're suggesting?"
"We put a wall of pillows down the middle!" Shizuka blurted out, her hands gesturing wildly. "It's a perfectly logical, sociological solution to a resource scarcity problem. We are both mature adults. We can share a mattress without... without incident."
Ren stared at her for a long beat. He noticed the way a stray lock of her damp hair curled against her neck, and the way her panda pajamas were slightly unbuttoned at the top. He cleared his throat and looked back at his screen.
"Fine. But if you talk in your sleep about Sociology theories, I'm kicking you off."
"I do not talk about Sociology in my sleep!"
Two hours later, the lights were out.
The "Pillow Wall" was a fortress of fluff standing between them. Ren lay on the right side, staring at the ceiling, every sense dialed up to eleven. He could hear Shizuka's rhythmic breathing. He could smell that intoxicating vanilla scent again, now amplified by the warmth of the blankets.
He shifted slightly, and the mattress groaned.
"Kurosawa-kun?" Shizuka's whisper was tiny, barely audible over the hum of the AC.
"Yeah?"
"Don't... don't think this changes anything. Tomorrow morning, when the sun comes up, I'm still your Professor."
Ren turned onto his side, facing the back of the pillow wall. "I know, Professor. But right now, the sun isn't up."
A moment of silence passed. Then, he heard her move. A small, soft hand reached over the top of the pillows, tentatively fumbling in the dark until it brushed against his arm. She didn't grab him; she just let her fingertips rest there for a second, as if confirming he was real.
"I'm scared," she whispered, her voice losing its professional edge. "What if we can't keep this secret for 100 days?"
Ren reached up, his hand covering hers. Her skin was soft and trembling. "Then we make sure the secret is worth the risk."
He didn't let go of her hand, and for the first time since the "404 Error," Shizuka fell into a deep, dreamless sleep. Ren, however, stayed awake for a long time, watching the moon crawl across the floor, wondering if he had just crossed a line he could never go back over.