Kotomi Izumi recognized the little box covered with magical girl stickers. Yuka often put things she considered precious inside it.
To adults, those treasures might seem trivial—perhaps a pretty princess sticker she liked too much to use, or an oddly shaped stone she found by a stream on her way home, wondering if it might have come from another world.
Kotomi understood perfectly. When she was little, she didn't collect stones or stickers, but whenever she saw a perfectly straight branch by the roadside, she'd snatch it up like treasure, afraid that if she hesitated even a second, someone else might take it first.
It was just an ordinary stick, yet little Kotomi would hold it as if she were a dark lord wielding a crimson magic sword. If she found a longer one, it became the legendary Spear of Longinus.
While other kids pretended to be shining heroes with holy swords and divine armor, saving the world in their daydreams—Kotomi was different. Even now, still proudly chūnibyō, she preferred imagining herself dressed in black, red light glowing from her eyes, leading a legion of the undead to bring about the end of the world.
Or perhaps as a dark antihero—ruthless, decisive, yet with her own twisted sense of justice.
Yuka opened the box lid. Kotomi glanced inside and saw a collection of crayon drawings—simple yet full of childlike innocence—along with a few small toys.
The box was packed full. As Yuka opened it, a few toys rolled out onto the floor.
Yuka's small hands rummaged through the box before stopping. She seemed to have found what she was looking for. Closing her fist around it, she held it out toward Kotomi.
"Penguin Onee-chan, this is for you."
"This is what you wanted to give me? What is it?"
Kotomi smiled, crouching down and opening her palm.
"It's something you forgot, Penguin Onee-chan."
Yuka loosened her grip. The small object she had been holding dropped lightly into Kotomi's hand.
Kotomi looked at it—a lace flower, delicate and familiar. After thinking for a moment, she remembered. Wasn't this from her underwear?
Her cheeks grew warm. It must have fallen off last time because Yui had been a little too rough.
Falling somewhere in the Yuigahama house was one thing… but realizing that Yuka had picked it up made Kotomi want to ask, How do you even know this lace flower belonged to me?
"Ah… this little flower must have come off one of my outfits," Kotomi murmured softly, carefully choosing her words to avoid saying it was from her underwear.
"Mhm," Yuka nodded seriously.
"Thank you," Kotomi said, placing the lace flower in her pocket while wondering whether she could somehow sew it back where it belonged.
"Last Saturday, when it rained—you came to our house and stayed the night. I found this lace flower the next morning, on Sunday," Yuka said calmly, her tone steady and expression neutral. "It had fallen on my sister's bed."
"Eh, really? Saturday and Sunday, huh…" Kotomi mumbled vaguely as she slipped the lace flower deeper into her pocket, trying to think of how to change the subject.
Before she could come up with anything, Yuka suddenly spoke again—her voice soft, but clear.
"Penguin Onee-chan, have you and my sister been doing that kind of thing all the time?"
Kotomi's eyes widened slightly at the question.
Just then, Yui's voice drifted down from upstairs: "Kotomi, I still can't find my scarf! I swear I left it on the chair… Yuka, go grab a bottle of juice for Kotomi, okay?"
Kotomi didn't know how to respond. Even for her, explaining something like this to a child was too embarrassing.
"It's not that we're doing it all the time… just pretty often," Kotomi replied softly.
Hearing her sister's voice upstairs and Penguin Onee-chan's quiet answer, Yuka lowered her head. Her hair fell forward, hiding her expression from Kotomi's view—but Kotomi could clearly sense the conflict and sadness in the little girl's heart.
No matter how much Yuka had acted as a playful matchmaker, she was still a child. She loved her mother and sister deeply—and she also loved Penguin Onee-chan, Kotomi Izumi. In her young heart, she wished Kotomi could become her new mom or her sister-in-law, so that they could all be one family.
For adults, the fact that Kotomi and Yui Yuigahama had become physically intimate meant that their relationship had grown closer—something happy and natural. But Yuka wasn't an adult. She was still a child—one who, no matter how sensible she might seem, still wanted to cling to her family.
Her mother was always busy, working long hours at the cake shop, earning money from both baking and illustration work to support the household. For as long as Yuka could remember, it was her older sister Yui who had taken care of her. That was why she depended on Yui so deeply—and why she was afraid of losing her.
To Yuka, Kotomi and Yui being together meant her sister would eventually leave—that the person who had always been there for her would be gone.
Yuka wanted her mother and sister to be happy. She wanted Kotomi to be part of their family because she knew Kotomi could bring happiness to both of them. She wanted Kotomi to become her family too.
But realizing that her sister and Kotomi were really together, that they were lovers—Yuka's feelings became tangled and conflicted. She wanted her sister to be happy, but she was also scared that happiness would take her sister away.
She was still too young to truly understand such things.
After hearing Yuka's question, Kotomi looked at her in surprise for a moment. Then a soft smile curved her lips as she gazed at the little girl with gentle, sincere eyes.
"Yuka, are you worried that I'll take your sister away from you?" she asked.
Yuka kept her head lowered and didn't respond. Gone was her usual bright, lively self. Her small lips pressed tightly together, a stubborn attempt to keep her tears from falling.
"I won't take her away," Kotomi said gently, her smile warm. "Because your sister belongs to you, Yuka."
Those words melted away the last of Yuka's resistance. Big teardrops rolled down her round cheeks. She wiped her eyes with her arms, her voice trembling as she asked:
"What about you, Penguin Onee-chan?"
Kotomi extended her arms and drew the crying girl into an embrace, softly stroking her back—her touch tender and reassuring, like that of both an affectionate sister and a caring mother.
"Penguin Onee-chan is your sister too, Yuka. Your mom and sister will never leave you, because they're your family—your home, your support. And I'll become your family and support too."
Yuka kept wiping her tears. She was usually good at holding them back, always trying to stay strong. But the warmth surrounding her now gently melted that strength away. In Kotomi's arms, the tears wouldn't stop.
Kotomi held her close, her voice soft and sincere.
"I won't take your sister away, Yuka. So… can you entrust Yui to me?"
"…Okay."
After asking Yuka to bring Kotomi a juice, Yui had finally found her missing scarf—it had been lying on her bed, hidden beneath the blanket she'd spread out earlier.
Once she found it, she hurried downstairs, asking her mother to tidy up her messy room later.
But before she reached the living room, she heard Kotomi and Yuka's voices—gentle, whispering. It sounded like they were sharing secrets.
Curious, Yui stopped and peeked from behind the wall, quietly listening to the conversation between Kotomi Izumi and Yuka Yuigahama.
As she listened, a soft smile spread across Yui's face.
...
Yui Yuigahama waited until Yuka had fully calmed down before stepping into the living room.
As her sister, she knew Yuka's personality well. No matter how sad she felt, Yuka would always hold back her tears until she was alone—crying quietly where no one could see. Just as their mother often said, Yuka was mature to the point of being heartbreaking.
Whenever Yui looked at her overly sensible little sister, she couldn't help but recall the bratty, spoiled version of her from years ago. The thought filled her heart with emotion.
Both Tomoka Yuigahama, as their mother, and Yui, as her sister, felt proud that Yuka had become so well-behaved—yet at the same time, they wished she could still act a little spoiled, like when she was younger.
After all, Yuka was still a child.
A child who becomes too sensible too soon can inspire both pride and heartache.
Yuka was exactly that kind of child—and it wasn't just her mother or sister who felt it. Even Kotomi Izumi found herself feeling a pang of tenderness every time she saw how mature Yuka tried to be.
Now, having wiped away her tears, Yuka greeted her sister as usual when she entered the room.
"Sis, you finally found your scarf? That took forever! You're so careless. If you keep being like this, Penguin Onee-chan might get tired of you."
"You little brat. That's not for you to worry about," Yui said with a smirk, grabbing Yuka's chubby cheeks and giving them a playful squeeze. "Have you gained weight again? I bet if I took you to a butcher, they'd pay good money for every kilo of you."
"Waaah—bad sister! Penguin Onee-chan, she's bullying me!"
"What? She's bullying my little Yuka? I'll have to punish her later," Kotomi said teasingly, glancing meaningfully at Yui.
As a "dog who had already tasted meat," Yui immediately caught on to the implication. She brushed her hair shyly and giggled with a blissful smile.
Yuka tilted her head in confusion. Sometimes she understood things, but sometimes she didn't—like now. Why was her sister smiling so goofily instead of getting mad or embarrassed after being teased? Does Sis really have something wrong with her head? she thought.
Sisters often had that kind of relationship—they truly cared for each other deep down, yet every time they met, they couldn't help but bicker.
After a few rounds of playful teasing, Yuka's mood was completely back to normal.
She had been worried that her sister would leave her now that she and Penguin Onee-chan were dating. But after talking with Kotomi, she realized something—neither her sister nor her mother would ever leave her side. In fact, she'd gained a new family member and someone else to rely on: Penguin Onee-chan.
The thought made her much happier. The heavy feeling in her chest that had lingered for so long vanished like dust in the wind.
...
After saying goodbye to Tomoka Yuigahama and Yuka, Kotomi Izumi and Yui Yuigahama walked hand in hand toward the station.
Kotomi glanced at her phone. There was still plenty of time. She wondered whether Yukino Yukinoshita had arrived yet—or if she had just left.
Yukino's apartment, Gokoku Residence, wasn't far from the station either. Kotomi had a natural gift for remembering locations, so she never worried about getting lost.
Once, when she had gone out with a friend to Setagaya, her friend—unfamiliar with the area—accidentally got lost.
Fortunately, Kotomi's sense of direction had saved them. She quickly led the way back to the right route.
Her friend, amazed, asked, "Kotomi, this is your first time in Setagaya too. How do you remember directions so well?"
Kotomi chuckled. "When we left earlier, I noticed a sushi shop nearby. I really wanted to eat there, so I memorized its name and signboard. Just now, when we realized we were lost, I spotted that sushi shop in the distance. From there, it was easy to find our way back."
Of course, Kotomi Izumi couldn't have memorized all the streets of Setagaya on her first visit. But she could remember the most striking buildings—and use them to find her bearings.
Kotomi often used restaurants as her mental landmarks.
From Gokoku Residence to the train station, there was a restaurant that specialized in grilled eel rice bowls. Because she remembered that unagi restaurant, she could easily recall the distance from the apartment to the station.
Gurururu…
Just thinking about eel rice made Kotomi's stomach growl.
Still, she decided to hold out a little longer—she'd eat once they boarded the Shinkansen.
As Kotomi's stomach grumbled softly, Yui Yuigahama, who was holding her hand, suddenly let go. She opened her backpack and pulled out a small disposable box. For this trip, Yui had brought both a suitcase and a backpack.
"Kotomi, I know one yogurt cake isn't enough for you, but it should tide you over for now," Yui said warmly as she lifted the lid.
The moment the lid opened, a soft, delicate aroma drifted out—not overpowering, but gentle and perfectly balanced.
Kotomi had never eaten yogurt cake before, but the scent alone was enough to tell her one thing—from now on, the only yogurt cake she would ever like was the one made by Yui Yuigahama and her mother.
She really wanted to eat it, but she put on a show of restraint. "I'm not that hungry yet. Maybe you should have it?"
Without hesitation, Yui pushed the box toward her. "It's for you. Remember yesterday when I said I wanted you to come over to try my yogurt cake? You didn't make it, but I still decided to bake a few anyway. The first few turned out kind of bad, so I let Yuka eat them all."
"Then this morning, I tried again—and I finally nailed it! But for some reason, Yuka refused to eat any more, no matter what I said."
"This one here is my best one—I made it especially for you, Kotomi."
Yui pursed her lips slightly, glancing at Kotomi with a faint pout. "What's wrong? Don't you want to eat it?"
!!!
Kotomi's resistance to cute-girl pleading was absolutely zero.
She was already a bit hungry—and now, with Yui's adorable coaxing, her appetite completely took over.
She grabbed the yogurt cake and devoured it in five quick bites. After licking the cream from the corner of her lips, Kotomi pulled Yui close and kissed her hard on the lips.
"The yogurt cake was delicious," Kotomi said with a mischievous smile, "but compared to you, you're sweeter—and taste even better."
"Then I'll make you yogurt cake every day, okay?" Yui's cheeks flushed red.
"If you make it every day, I'll get tired of it," Kotomi said playfully. "Well, getting tired of cake isn't the real problem—I'd be more worried about you getting exhausted. I've baked cakes before; I know it's not easy. I'd feel bad if you wore yourself out. So instead, how about letting me have my cute, silly dumpling every day? I'll never get tired of that."
She lightly tapped Yui's nose, smiling sweetly.
Then—
Kotomi was suddenly pinned against the wall by Yui.
And the next moment—
Yui kissed her hard.
The once slightly dominant Kotomi was instantly reduced to a soft, clingy little wife in Yui's arms.
This little "top" who always claimed she was probably the aggressive one now wrapped her arms around Yui's neck, whining for more kisses and cuddles.
—
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