In another room, a young girl with long white hair cascaded over the pillow.
She was Shirogane Kei, one of the three surviving humans still holding on.
Kei's beautiful face appeared peaceful in her sleep, a stark contrast to the post-apocalyptic world outside the window. Though she didn't have the habit of sleeping naked, her sleepwear was more provocative than nudity.
The shorts she wore were so mini they barely covered her buttocks, while the thin, transparent t-shirt revealed the silhouette of her slender body. For those paying closer attention, the V-shape at her crotch and the hardened points on her chest protruding through the thin fabric would be visible. Clearly, this girl wasn't wearing any underwear at all.
Suddenly, Kei's eyelids fluttered. Her crystal-blue eyes opened with an unfocused gaze.
"Toilet..." She murmured softly.
With a lazy movement, she rose from the bed and shuffled out of the room. Yawning widely, her only intention was to empty her full bladder.
However, just a few steps into the corridor, her footsteps halted.
"What sound is that? So noisy."
Still not fully awake, Kei sharpened her hearing. She worried that perhaps a monster had managed to sneak into the house. After all, it wasn't the first case; they always had to stay vigilant.
But as she got closer to the source of the sound, what she heard became clearer. Kei might not have experienced intimate relations herself, but that didn't mean she lacked knowledge about it.
(Wait a minute...! This sound...)
Instantly, her drowsiness vanished like it was swept away by the wind. Moans and groans, accompanied by the sound of two bodies colliding, rang clearly in her ears.
(Maybe I'm hearing things? This often happens in anime.)
(Charlie-san and Aishia-san's relationship is more than just friends, but not dating. Otherwise, in this past year, something like this would have happened before! Why now? This must not be what I'm imagining.)
Reassuring herself not to jump to conclusions hastily, Kei walked slowly and silently toward the source of the sound.
Charlie's door wasn't fully closed, leaving a gap large enough to peek through. Carefully, Kei brought her eye to the door crack.
Instantly, her eyes widened. Her hand reflexively covered her mouth, which nearly screamed.
The sight before her made breathing difficult.
Inside the room, on the now-messy bed, Charlie was riding Aishia in the most primitive and dominant position.
"Ah... Charlie... deeper... deeper..."
Aishia's usually monotone voice now carried a tone full of desire. Her hands gripped the sheets tightly, her smooth legs wrapped around Charlie's back.
"..."
Kei couldn't look away. On one hand, she felt ashamed and guilty for peeking at something like this. But on the other, there was an irresistible curiosity. This was the first time she had witnessed a man and woman in intimate relations directly.
She noticed how blood rushed to her own face, feeling the heat spreading throughout her body. Her shorts suddenly felt tight, and there was a strange sensation between her thighs. Unconsciously, her hand touched her own chest, feeling her heart pounding wildly.
(So... Charlie-san and Aishia-san really...)
As Charlie changed positions, Kei could clearly see Aishia's expression—a face filled with satisfaction. The blood on the sheets, the sweat on their bodies, and the faint musky scent reaching Kei's nose all formed an undeniable reality.
(So Aishia-san can make an expression like that...)
That thought swirled in Kei's head as her eyes remained glued to the door crack. Rather than returning to her room, her feet felt rooted in place.
Over the year of their companionship, Aishia and Est had almost always shown flat expressions—like beautiful dolls without emotions. But now... Aishia's face was filled with uncontainable satisfaction, her lips parted emitting moans that made Kei's heart race.
(Is sex really that amazing?)
Kei felt her throat dry. At her age of nearly 17, her curiosity about sexual matters was at its peak. Her classmates used to whisper about adult films, but she always pretended not to be interested.
But now...
(Something that big going in and out of Aishia-san? So scary...)
Unconsciously, Kei's hand touched her thin shorts. A strange wetness began seeping through the fabric. Her fingers trembled as they touched the sensitive area, and she held her breath as she watched Charlie move faster.
"Aishia... you're so... hot..."
Aishia's response was only a long moan that further burned Kei's ears. She watched how Aishia's body arched, how her fingers gripped the sheets, how her smooth legs locked around Charlie's back.
(I wonder if something that big would fit inside me?)
That thought made her body even hotter. Her middle finger began rubbing slowly through the fabric of her shorts, pressing right on the most sensitive spot. An electric sensation spread from there throughout her body. Kei had to press her left hand to her mouth to stifle a moan.
From behind the door, she saw Charlie change positions—now Aishia was on top, her long pink hair waving wildly following her body's movements.
Aishia's expression was truly... intoxicating. Her usually pale face was now flushed, her eyes half-closed, her lips parted with a small tongue occasionally licking her upper lip.
"Charlie... I... I'm going to..." Aishia suddenly cried out, her body trembling violently.
Kei could no longer hold back. She unbuttoned her shorts and inserted two fingers directly into her already wet self. Her movements quickened, following the rhythm from inside the room. Her breaths became short and ragged, sweat beading on her temples.
She watched how Charlie gripped Aishia's hips firmly, pushing deeper. Their moans now became one, uniting in perfect harmony. Kei felt something tightening inside her, like a spring about to release.
"Ah... ah... Charlie-san..." Kei gasped unconsciously, her fingers moving faster.
Suddenly, from inside the room, a long cry from Aishia was followed by a deep groan from Charlie. At the same moment, Kei felt a tremendous explosion within her. Her body trembled uncontrollably, her legs nearly unable to support her weight. She had to lean against the wall to avoid falling.
When she opened her eyes again, from behind the door crack, she saw Charlie and Aishia embracing, their bodies still connected, their breaths heavy. There was blood and other fluids between Aishia's thighs, but they looked happy.
Kei quickly pulled up her shorts, a sudden wave of shame overwhelming her.
What had she just done?
Masturbating while peeking at others?
Her cheeks burned red. But behind the shame, there was a strange satisfaction tingling throughout her body.
She turned to return to her room, but before leaving, she glanced once more inside. Charlie was now stroking Aishia's hair with full affection, something she had never seen before.
(Could... I feel that someday too?)
That final thought made her blush again before she quickly walked away from the spot, leaving the two lovers still bound in their tender embrace.