Early in the morning, at exactly 6 a.m., Kikukawa Yuu was roused from sleep by the sound of her alarm. Half-awake, she groggily went through the motions of brushing her teeth, washing her face, and getting ready to head out and open the bookstore.
As she passed by the study, Yuu heard a faint rustling noise coming from behind the door.
Since their parents were often away for work, it was natural that they weren't home now. They had been especially busy these past few days, so the only possible person in the study at this hour was her little sister.
The combination of Kikukawa Kyo and study immediately triggered some rather unpleasant—perhaps even a little terrifying—memories for Yuu.
God knew how shocked she had been when she first saw the so-called archive wall that Kyo had set up in there—a massive whiteboard completely covered with photos. And not just photos, but also highly detailed personal information about each individual. Hobbies, favorite sports, academic abilities… nothing was left out.
That was when the archive wall was still in its early stages. At the time, it lacked Kyo's later additions: behavioral analysis, counter-strategies, and other chillingly meticulous observations. The second time Yuu checked it, she was stunned all over again by the sheer depth of the data.
If this thing ever shifted its function from research to a hit list, Yuu had no doubt that Tokyo would soon be dealing with one—or multiple—unsolvable murder cases.
Nope, she needed to go in and check. Just in case her little sister had suddenly decided to take inspiration from infamous serial killers.
Carefully pushing the door open, Yuu found exactly what she expected—Kyo was sitting cross-legged on the floor in front of the archive wall, hunched over a sheet of paper, scribbling something down.
"Nee-san, could you get me a glass of water?"
Kyo didn't even turn around. It was as if she had eyes in the back of her head.
"...How did you know I was here?" Yuu had been trying to sneak up on her, but she'd been caught immediately.
"Next time, remember to fake the sound of walking away first," Kyo replied without looking up, still focused on whatever she was working on.
Sharp little brat...
Resigned, Yuu left the study and headed to the dining table.
Although their family only had four members, there were seven cups on the table. Four of them were placed neatly together, each a different color, arranged in descending order of size. The other three were scattered randomly around.
The four cups grouped together all belonged to Kyo, while the remaining three were for Yuu and their parents.
The reason Kyo had four cups was simple: aside from the one she used herself, the other three were designated for the rest of the family to pour drinks for her.
Every morning, whoever was home would prepare a drink for Kyo—sometimes just a cup of water, sometimes tea or coffee as a little surprise. It had become a fixed family routine.
But today, with only the two sisters at home and Kyo waking up particularly early, she hadn't gotten her usual morning drink yet.
Yuu decided not to just pour her plain water. Instead, she crouched down and rummaged through the storage box under the dining table, pulling out bottles of Sprite, bayberry juice, and oolong tea—just your typical convenience store drinks.
For the record, their house had multiple boxes like this scattered around. Under the dining table, beside the fridge, next to the couch by the balcony—practically every few steps, there was another stash. And, of course, the largest collection was in Kyo's own room, stuffed into her closet.
As for her clothes? Well, those had all been crammed into Yuu's wardrobe instead. Fortunately, Kyo's outfits were mostly dress shirts and long pants—not that Yuu minded, since she liked wearing them too. They had a few different styles mixed in, but even if their clothes ever got mixed up, neither of them would really care.
Yuu plopped a few ice cubes into a cup, then poured in the three drinks one after the other. Simple as that, the beverage was ready. Kyo had actually taught her this easy method for making fruit-infused sparkling tea. Yuu never really measured the proportions, but she had tried it before, and it tasted surprisingly good.
Mixology wasn't that complicated, after all.
Carrying the makeshift oolong soda, Yuu walked back to the study. By then, Kyo had already stood up and was pinning her freshly written notes onto the archive wall.
Kikukawa Yuu glanced at where her sister had placed the new addition on the archive wall—it was pretty close to the center. That piqued her curiosity. Who did she add this time?
By now, Yuu had picked up on a few patterns regarding this wall. The photos placed toward the outer edges typically belonged to people Kyo either wasn't close to or rarely interacted with, meaning there was no need for in-depth analysis. Some were just shallow personalities, predictable enough that no special strategies were required to handle them.
The closer to the center, the more significant the individual.
After sticking the note in place, Kyo took a few steps back and happily accepted the fizzy fruit tea from Yuu's hand, sipping it contentedly while Yuu took the opportunity to check the new names.
"Sumita Mana, Misumi Uika, and Yuutenji Nyamu."
Yuu immediately recognized Nyamu as the woman who went by "Nyamuchi" online. The other two seemed to be part of an idol group. Didn't Mom recently collaborate with them? Yuu vaguely recalled looking them up out of curiosity.
"They're pretty central on the board. Looks like you think highly of these three?"
"Mm. I'll probably be dealing with them often in the future—part-time jobs, collaborations, things like that."
The tea, already good on its own, was made even better by the tangy sweetness of the bayberry juice and the light fizz of the Sprite. Kyo took slow, deliberate sips, savoring each one. No matter how many times she drank it, each mix had a unique taste, something more than just quenching physical thirst.
She treasured this taste—the flavor of being cared for.
With her teeth gently resting against the rim of the cup, Kyo stepped behind Yuu and leaned her forehead against her sister's back.
Feeling Kyo's rare display of emotion, Yuu let out a sigh, her eyes drifting back to the archive wall.
Good thing Kyo has ways to process her emotions, even if it's through unconventional methods like drinking water. At least she has me, Mom, and Dad to support her. If she didn't…
Yuu didn't want to finish the thought. She feared Kyo would have become someone who only responded to people with mechanical precision, devoid of real connection.
"Alright, alright. What's with you getting up this early? You're not usually this diligent about updating the archive wall."
Turning around, Yuu reached out and ruffled Kyo's pearl-gray hair. It was loosely tied back, making it easy to mess up. The strands tumbled free, cascading over her shoulders.
Kyo frowned in protest, swatting at the hand still tousling her head. She shook her hair, trying to get it to settle naturally again, then continued sipping her drink in small, measured gulps. Yuu simply waited, knowing her sister wouldn't answer until she finished.
And sure enough, after practically licking the last drops from the inside of the cup, Kyo finally set it down and responded.
"I had a new idea. Maybe if I completely mimic someone, I'll be able to understand how they think. I woke up early to look through the archive wall for a good candidate to imitate."
Saying this, Kyo hesitated, glancing up at Yuu. With their height difference, her gaze naturally tilted upward.
"Would you find that… weird?"
"A little."
Yuu didn't bother sugarcoating it. She knew better than to lie to this sharp little fox. If Kyo caught even the slightest hint of dishonesty, it would only make her overanalyze things.
"But honestly? Coming from you, it doesn't feel all that strange." Yuu laughed and gestured at the archive wall. "I mean, I've gotten used to this thing already. This idea of yours? It's actually very you."
After thinking for a moment, she added, "It's kind of cute, actually. That awkwardness of trying to learn emotions."
"Cute…" Kyo's lips barely left the cup as she mumbled through another sip of tea, the carbonation adding a faintly bubbly texture to her words. "So you don't think I can succeed?"
"I think you can mimic someone perfectly. You can even predict how they'd react to situations based on their habits. But that's exactly why I don't think this method will help you cross that final barrier of understanding."
Yuu pulled Kyo into a light hug. It wasn't the same as offering her a drink, but physical gestures could sometimes communicate things better than words.
"Your mimicry relies on logic. But there's an inherent gap between rationality and emotion. Trying to grasp emotions through imitation alone will only take you further from truly understanding them."
After a brief pause, she added, "But if it's you, I still think it's worth trying."
"Even though you just said it won't work?" Kyo's muffled voice came from within Yuu's arms.
"Because you're Kikukawa Kyo," Yuu chuckled. "For all I know, you'll bulldoze through every obstacle in your path and somehow make it work."
"'Bulldoze through everything'… That sounds more like you, Nee-san. You're the one with freakish strength." Kyo wiggled, trying to free herself. Being hugged made it harder to drink.
"Hey, don't change the subject! I was trying to comfort you, and now you're out here slandering me."
With a small thunk, Yuu flicked Kyo's forehead. Then, her tone softened, growing serious again.
"What I'm trying to say is—do whatever you want to do. Even if you exhaust every method and still can't grasp emotions, you can always choose to feel them instead. Stop worrying about what kind of feelings they are, just let them happen."
"You do realize I've hurt people before by expressing things the wrong way, right?"
"And you've also healed people—without even realizing it—simply by acting on your emotions."
To Yuu, Kyo was like water. She could be an unstoppable force of destruction, but more often than not, she was something else entirely.
She was the rain after a long drought. The wave that pushed a stranded boat back to sea. The steady stream that nourished life.
"And besides—Mom, Dad, and I will always be here for you. You're not some lost, wandering tide with no shore to return to. Whenever you're tired, you can always come home."
Yuu smiled and tapped Kyo's forehead again.
What she didn't say aloud was—this little brat has no idea how many people have already fallen for her, just from her natural way of being.
Honestly, Yuu felt bad for them. If Kyo didn't learn how to properly recognize emotions, she might just end up a completely unintentional heartbreaker.
"...Why does it sound like you're saying that out of sheer resignation, like you've just given up?" Kyo deadpanned, blinking.
"I'll remember what you said," she continued after a moment, "but for now, let me try my way first."
"Oh my god, are you blushing?"
"Get lost—!"