When Aimi stayed behind, Kotomi Izumi didn't think much of it. She was already used to it—her little sister wanting to spend some time in her room wasn't anything unusual.
Even though she knew the feelings Aimi held for her weren't entirely ordinary…
Aimi often stayed in Kotomi's room for a while, doing nothing in particular—just sitting or lying together on the bed, each occupied with her own thing, occasionally exchanging a few words.
Kotomi knew Aimi had recently gotten hooked on gal games. Last time, she had even forgotten to do her homework because she'd been playing too long.
As someone who had once been a hopelessly addicted gamer herself, Kotomi didn't exactly have the right to lecture Aimi about playing too many games. Still, she would sometimes gently remind her that the high school entrance exams were coming up in February. Even if she wanted to play, she should focus on studying for now—then play as much as she wanted afterward.
If Kotomi wanted to, she could easily support Aimi for life, even if she quit school right now.
But Aimi had her own life to live. As an older sister, Kotomi hoped she would one day find something she loved to do and achieve her own success.
Kotomi understood Aimi's feelings for her very well. That feeling… was love.
But love wasn't about clinging to someone day and night, to the point of complete dependence.
Love was like a fine wine that needed careful balance—too much or too little of any ingredient, and its flavor would turn strange.
True love was mutual, equal, and reciprocated.
"Want to sleep together tonight?" Kotomi asked with a soft laugh as she looked at Aimi, who was still sitting quietly by the bedside, lost in thought.
She switched her phone to "Do Not Disturb." Since she didn't have to wake up early tomorrow, she could finally sleep in.
In the past, Kotomi would've stayed up late playing games—but now, all she wanted was to lie in bed and drift off while doing absolutely nothing.
"Okay." Aimi nodded. No wonder she'd been sitting silently by the bed—it turned out she was waiting for Kotomi to ask.
Kotomi found that kind of thing cute—if Aimi wanted to sleep together, she could've just said so. It wasn't that she was being shy; she just liked to feel like she had the upper hand, waiting for Kotomi to bring it up first.
This little schemer… you're too adorable for your own good, Kotomi thought fondly.
They lay down together. The winter quilt was large, so even with both of them under it, there was still plenty of space.
After a short silence, Aimi spoke.
"Onee-chan, you've seemed kind of distracted lately. Did something happen?"
So she noticed, huh?
Kotomi wasn't surprised. Aimi could be a bit of an airhead sometimes, but most of the time, her mind was sharp and quick. Even though she spent a lot of time playing gal games lately, her grades had never dropped. In fact, she had just ranked first in her entire class on the last mock exam.
Aimi's homeroom teacher—who had also been Kotomi's teacher in middle school—was the kind and easygoing Ms. Hiiragi Kawano. She had even said:
"With Aimi's grades, she has at least an 80% chance of getting into the high school division of Sakuraka Girls' Academy. I just don't understand why she doesn't seem interested in applying there."
Soon, the time would come for Aimi to fill out her final application preferences. This round was critical—it would determine which schools she could ultimately apply to.
That made it even harder for Kotomi to criticize her for being absorbed in games. After all, when she'd been in her third year of middle school, she had consistently ranked dead last in her class.
Back in her first and second years, she'd been third from the bottom—but when the two students below her either transferred or dropped out at the start of her third year, Kotomi had proudly inherited the title of "last place" all the way until graduation.
Fortunately, the goddess of luck had smiled on her during her high school entrance exam. Her guessing game on the test had gone surprisingly well—just like a blind cat catching a dead mouse—and she'd managed to scrape together enough points to barely meet the cutoff for admission to Sobu High School.
Otherwise, with Kotomi's grades back then, she probably would've needed to spend a bit of money to get into high school.
"You noticed, huh? It's nothing serious… It's just that a friend of mine left—she went to another country. It'll probably be a long time before we can meet again," Kotomi said softly.
"Was it a guy or a girl?"
"A girl."
Kotomi answered quietly. Since Aimi had noticed, she felt she should at least give her a simple explanation.
But she didn't reveal Kazumi's true identity—nor did she mention her name.
It wasn't because she feared Aimi would think she'd gone crazy, but rather because Kotomi knew that even if she told her, "My friend's name is Kazumi—she's a girl who called herself a system and used to live inside me," Aimi would probably still believe her.
Even if it sounded impossible, even if from a normal person's point of view it was just a waste of time, Aimi would still accompany her without hesitation—willing to waste time together with her sister.
Kotomi decided not to tell her—not yet. When the day came that she reunited with Kazumi, she'd introduce her to the family properly.
When that time came… how should she even describe their relationship? Kotomi wondered to herself.
"Hey, Aimi," she said suddenly, "if someone asked you to help them find their true self, what would you think?"
Three heads are better than one, after all. Two people thinking together was surely better than one person frowning alone. Maybe, just maybe, Aimi's thoughts could spark a new idea.
"This was something your friend asked you to do before she left, right?" Aimi asked casually.
Hey, little Aimi—are you really my sweet little sister? Do you have to be this perceptive? Kotomi thought wryly.
After a short pause, she nodded. "Yeah. That girl just had to say something like that before she left… Was she trying to make sure I'd never forget her?" she said with a helpless smile.
But Aimi could hear it—the soft undercurrent of longing beneath her sister's light tone.
For someone to make her sister miss them this much after parting… that friend must have been very important.
And she was a girl.
Could their relationship really have been just friendship? The thought made Aimi's chest tighten with jealousy. Whenever she heard about a close female friend of Kotomi's, she couldn't help feeling envious.
No, no—that's not the point right now! she scolded herself internally. Her sister clearly misses her friend a lot—I shouldn't be sulking right now. Of course she can have close female friends who mean a lot to her!
"Finding your true self, huh… sounds like some kind of riddle to solve," Aimi mused.
"Yeah, exactly. And I've always been terrible at riddles," Kotomi said with a sigh. "When I play mystery games, I always have to look up guides. At least those games give you clues or context—some kind of hint to work with. But this one? There's nothing at all."
She let out another long sigh of frustration.
"Maybe your friend meant that the version of herself living here isn't the real her," Aimi said thoughtfully. "That she's unhappy with who she is right now—or how she's living—and believes somewhere out there, in another corner of the world, there's a happier, truer version of herself."
As Aimi spoke, she quietly reached under the blanket and held Kotomi's hand, pretending as if nothing happened. Her face remained innocent, eyes fixed on the ceiling.
Kotomi, half-amused, tried to pull her hand away just to tease her—but Aimi only held tighter, as if afraid her sister might run away, scooting closer until the distance between them disappeared completely.
"If this were a riddle," Aimi continued softly, "the answer should probably be simpler. Maybe I'm not thinking in the right direction, though. It might have something to do with psychology. But honestly, my knowledge of psychology barely fills half a cup—I doubt I can help much, Onee-chan."
"No, you've already given me a lot to think about. Thanks," Kotomi said gratefully.
Unsatisfied with herself…? That didn't sound like Kazumi at all. The Kazumi she knew was more narcissistic than even she was.
When she thought about it, she realized that the time she'd actually spent with Kazumi hadn't been that long. On the surface, Kazumi always seemed cheerful and playful—but did Kotomi really understand her? Were there parts of her heart still hidden, things she'd never spoken about?
"As long as I can help you, Onee-chan," Aimi said softly.
"By the way, Aimi, do you actually know anything about psychology? Are you interested in it? Planning to study it in university?" Kotomi asked, half-teasing, half-serious. "If you do, you'll need to work hard on your English—and maybe another foreign language too. A lot of academic psychology books and research papers are only available in their original languages, with no translations."
Kotomi was already imagining what Aimi would look like in college—walking to a lecture hall with thick textbooks in her arms, glasses perched on her nose, a soft breeze lifting her hair.
Aimi chuckled and shook her head. "No plans to study psychology. And Onee-chan, you're thinking way too far ahead. I haven't even decided which high school to apply for yet, and you're already worrying about my college major?"
"It's not too early to think about college, you know. Don't be fooled by the fact that high school's also three years—those years fly by fast."
"But Onee-chan, you haven't even finished high school yet yourself."
"Just let me sound cool for once, alright?" Kotomi said, puffing up her chest slightly.
Aimi smiled helplessly but affectionately. Under the blanket, she tightened her grip on Kotomi's hand, as if afraid she might slip away.
It reminded Kotomi of when they were little—when Aimi had once held her trembling hand tightly after they'd gotten lost, comforting her as she cried in fear.
"Onee-chan," Aimi said softly after a moment, "about what your friend asked you before she left… I think there might be another possibility."
"What is it?" Kotomi's drowsiness instantly vanished. She sat up a little, eyes bright with curiosity.
It wasn't desperation—just that she had so little to go on. Every new theory, every idea, could bring her closer to fulfilling Kazumi's final request.
"Maybe," Aimi began gently, "your friend made that riddle sound so vague and gave you no clues at all… not because she really wanted you to find her true self. Maybe she knew you'd never meet again. She didn't want to hurt you with the truth, so she gave you a difficult task—to distract you, to give you something to hold on to. So that by the time you realized you'd probably never see her again, the sadness would hurt a little less."
"Onee-chan… maybe she wasn't asking you to find her true self. Maybe she was saying goodbye—in the gentlest way she could."
"Stop it!"
Kotomi suddenly sat up, her voice trembling, her lips quivering as she shouted.
She had already considered that possibility—the idea that Kazumi might never wake up again, that they might never meet—but she refused to accept it. She couldn't.
No—if she could just find the real Kazumi, then the Kazumi sleeping inside her would surely awaken again.
Or maybe she would wake even before that.
"Onee-chan…"
"Don't—don't say that again," Kotomi said, her voice breaking as she hugged her knees to her chest and curled up against the wall. "She's just… she's just gone for a little while, that's all. You've never met her, so you don't understand. She could be annoying sometimes, but… but she always kept her word. Always…"
Her voice cracked, her tone fragile—like a child afraid of the dark.
"…She's really that important to you, huh? Someone that important… and I've never even met her."
Aimi whispered so softly that only she could hear. Then, she sat up too, pulling the blanket around them both before wrapping her arms around her sister.
The thick quilt covered them completely, like a small, warm barrier against the world.
"To me," Aimi murmured quietly, "it feels like I just found out that there's some woman I've never met—someone who's suddenly become irreplaceable in your heart. It doesn't feel good at all. I'm… jealous of her. So jealous. But she didn't even give me the chance to be jealous—she just vanished without a trace. She left such a deep mark in your heart… and I don't even know her name, or what kind of person she was."
"…Aimi, I'm sorry. I got too emotional just now," Kotomi whispered.
"If you really feel sorry," Aimi said softly, "then stop thinking about anything else. Just hold me—and sleep."
In the silence that followed, Kotomi slowly wrapped her arms around her sister in return.
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