Perhaps Yukinoshita Yukino was that fated existence in Narumi's life within this simulation.
Like a princess kidnapped by an evil dragon, waiting to be rescued; like a "drop-in-from-the-sky" classmate who plays mind games with the protagonist in a romantic comedy; like the true heroine whose route only unlocks after clearing every other character's ending.
Was it troublesome to romance Yukinoshita Yukino?
Yes. Extremely troublesome.
But—
She was flat-chested + black long straight hair.
A perfectly shaped chest that didn't jiggle with any unnecessary excess, small and delicate yet still unmistakably girlish. Pair that body with loose, boyfriend-style shirts, and top it off with flowing, glossy, pleasing-to-the-eye long black hair—yeah, she bounced back and forth inside Narumi's strike zone nonstop.
If there really were such a thing as a dating-sim game, she'd absolutely be Narumi's first "best girl."
"It's just a romance game, right? Playing with feelings sounds pretty fun."
Narumi Tōru voiced his opinion without the slightest hesitation.
[It appears this simulation has applied a rather questionable personality modifier to you, but I am pleased to learn that you have chosen to retry.]
After the system's voice faded, the distorted world around him snapped back into reality.
Narumi blinked—and found himself once again standing in front of Yukinoshita Yukino's hospital room, precisely at the moment before he opened the door.
"Hey, what're you spacing out for, Achē? Don't tell me you're getting shy."
Yukinoshita Haruno teased him with a bright smile.
"Not at all. I was just worried—what if I'm so handsome your little sister falls in love with me at first sight?"
"Yukino? Pfft. You're probably not her type. Besides, I usually make sure smooth-talking, hot-on-the-outside-cold-on-the-inside guys stay far away from her~"
"Thanks for not denying that I'm handsome. Clothes make the man, and I also come with a complimentary silver tongue."
"Being good with words is a plus—but if you start sweet-talking Yukino, I won't let it slide, okay~"
Haruno said it smiling, light and cheerful—but Narumi knew that in her vocabulary, this was much closer to a warning.
He raised an eyebrow, gave her a crooked grin, and then—perfectly naturally—pushed the door open again.
Just like before, Yukinoshita Yukino lifted her gaze from her quiet reading and looked at him.
"Yo. Long time no see."
The curly-haired boy smiled and waved at her.
"Do you remember me, Second Miss Yukinoshita?"
"…Ah. You're my sister's extremely troublesome ex-boyfriend, right?"
After a moment's thought, the doubt vanished from Yukino's face. Her tone wasn't cold, but her eyes clearly held complicated emotions.
For Yukino, if there was any relationship that differed from the past, it was this man—her sister's once-inseparable high school lover.
The suddenly-appearing former boyfriend of her sister in this simulation had always been someone she couldn't ignore.
Someone who didn't care about others' gazes, acted on impulse, always wore an easygoing smile that never reached his eyes—unpredictable, hard to read.
He was the only unfamiliar existence in this simulation.
Which meant he was definitely not just background filler.
Now, about the Yukinoshita family.
Anyone who knew them understood that the relationship between the two sisters had always been… delicate.
An older sister who deeply loved her younger one, but expressed it by suppressing her to push her forward—and a younger sister who admired and yearned to surpass her sister, yet felt inferior whenever she stood before her.
If this were a yuri story, they'd be a deliciously twisted, taboo sister-pairing.
Unfortunately, Narumi Tōru appeared before them as Yukinoshita Haruno's boyfriend—and his presence only made their relationship…
Even more twisted.
"If I remember correctly, you two are already in the past tense, right?" Yukino raised an eyebrow, her words neatly matching the warped atmosphere.
"Then why is Narumi-senpai still here?"
"And you deliberately brought him to see me," she continued. "Does that mean you're giving me permission to make a move on Narumi-senpai?"
See? Things got weird exactly as expected.
"Oh my, if it's my beloved little Yukino, I wouldn't mind at all~"
Haruno's reply cranked the weirdness up another level.
"Yeah right. My taste isn't the same as yours, Onee-san."
"…So, uh—am I being treated as a get-well gift?"
Narumi tilted his head, looking harmless enough to fool a saint.
"Well, more accurately, I've been a bit busy lately," Haruno said smoothly,
"so I asked Achē to help look after Yukino for me."
Naturally, she wasn't about to reveal her real intentions in front of her sister—even though she knew perfectly well that such a polished excuse wouldn't fool Yukino.
"And you two haven't seen each other in a long time, right?"
"…We weren't close enough to need to see each other in the first place."
After a long silence, Yukino turned her face away, her voice sounding indifferent.
Narumi didn't call her out—his gaze merely drifted, accidentally catching sight of the IV line taped to the back of her hand.
In that moment, he finally understood one of Haruno's reasons for bringing him here—
This might be end-of-life emotional care.
"Oh come on, don't say that. Achē came because he's worried about Yukino's condition too, right?"
When Narumi snapped back to reality, a soft sensation wrapped around his left arm, and a familiar fragrance gently slipped into his nose.
Haruno naturally looped her arm through his, smoothing things over with her uncooperative little sister.
"That aside, Yukino looks like she's in good spirits."
Reading the room perfectly, Narumi broke into a bright smile and charged—sunny, friendly big-bro energy—straight into the social safety zone Yukino had built for herself.
"Since I've got time anyway, how about we chat for a bit?"
"...…?"
Yukino turned toward him, her face full of shock. She caught the deeper meaning hidden beneath her sister's smiling expression.
"Well then, I won't disturb you two. I've got my own things to take care of~"
…Yep. She'd been played.
Those two together probably had about eight hundred schemes between them.
Yukinoshita Yukino lifted her head with a headache, looking at the limited-time NPC who existed only in this simulated world.
With her mind occupied by how to face such a bleak future, she had no time to build emotional bonds with NPCs—
Especially when that NPC happened to be her sister's ex-boyfriend.