The Monday morning sun hung low over Sainan Town, casting long, golden shadows across the pavement as the students of Sainan First Elementary made their way to school. The air was filled with the specific, dusty scent of chalk and the high-pitched energy of children dreading the start of another week.
But for Yuuki Mikan, the world felt entirely different.
She walked through the school gates not as a student, but as a conqueror returning from a successful campaign. Her stride was light, floating on a cloud of euphoria that made her school bag feel weightless. Her usual reliable, somewhat serious expression had softened into a look of serene, untouchable satisfaction.
Every step she took sent a tiny, delightful vibration through her body. It wasn't just the lingering soreness in her legs, a sweet, secret reminder of the marathon session she had shared with her brother just twenty-four hours ago. It was the Golden Heart Seal.
Hidden beneath the fabric of her cute dress, specifically under the pleats of her navy skirt and the soft cotton of her panties, the seal glowed with a faint, rhythmic warmth against her lower abdomen. It was a physical weight, a magical brand that hummed in tune with her heartbeat. It whispered to her constantly: You belong to him. You are his Foundation. You are the Exclusive Sister.
Mikan hugged her schoolbag tighter to her chest, fighting back a giggle that threatened to bubble up.
'I'm a wife,' she thought, the words sounding dizzyingly sweet in her mind.
She replayed the last week in her head. It hadn't just been last night. For the past seven days, ever since she had broken down crying about being left out of the Harem Plan, Rito had been drowning her in affection.
He had bathed with her every night, washing her back with hands that lingered a little too long. He had kissed her goodnight, real kisses, soft and lingering, that left her dizzy. He had spent hours caressing her body, learning every sensitive spot, and even... went down on her, bringing her to tears of pleasure with his tongue while whispering how much he loved her.
She had been hooked. She had craved it. But it hadn't been enough.
'I wasn't satisfied with just that,' Mikan thought, a fierce pride swelling in her chest. 'I told him. I told him I didn't just want to be the pampered sister he fooled around with. I wanted the Seal. I wanted to be an Official Wife.'
And last night, he had given her exactly what she asked for. He had taken the final step, making her his in every way possible.
'I kissed him goodbye,' she thought, a fresh blush heating her cheeks. 'On the lips! Like a real wife!'
She entered the shoe locker area. The metallic clang of locker doors and the chatter of students usually annoyed her on Mondays. Today, it felt like background noise in a movie where she was the main character.
"Good morning, Yuuki-san!" a passing boy stammered, blushing furiously as he bowed.
Mikan blinked, turning to him. In the past, she would have given a polite, slightly distant nod, creating a barrier of maturity. Today, she beamed.
"Good morning!" she chirped, her smile dazzling enough to blind him temporarily.
The boy stumbled back, clutching his chest as if shot by Cupid's arrow. Mikan hummed and walked away, swapping her outdoor shoes for her uwabaki slippers. She felt generous. Rito's affection had filled her up so completely that she had extra kindness to spare for the others.
She slid open the door to Class 6-B.
The classroom was a riot of noise. Boys were wrestling in the back corner, girls were trading stickers near the blackboard, and the teacher hadn't arrived yet.
Mikan walked to her desk in the middle row. She sat down, smoothing her skirt carefully over her thighs, mindful of the precious seal underneath. She pulled out a fashion magazine she had borrowed from Run, Gal's Monthly, and propped it open. She wasn't really reading the article about "Summer Nail Trends", though. She was just enjoying the feeling of existing in this new, perfect reality.
Two desks away, Sachie and Mami were watching her.
They had arrived early, ostensibly to finish homework, but in reality, they were paralyzed by observation. They had been friends with Mikan for a long time, but the girl sitting a few feet away felt like a stranger.
Sachie sat with her chin resting on her hands, her eyes narrowed. Her brown hair twitched with agitation.
"Mami-chan," Sachie whispered, shielding her mouth with her hand as if to avoid Mikan noticing. "Do you see it?"
Mami, sitting at the desk next to her, nodded slowly. She was chewing on the end of her eraser, a nervous habit she had picked up since the sleepover months ago. "I see it, Sachie-chan. She's... shiny."
"She's not just shiny," Sachie hissed. "She's glowing."
Mami whimpered softly. "Do you think... do you think she finally did it? Like, for real?"
"Of course she did," Sachie gritted her teeth, her grip on her pencil tightening until her knuckles turned white. "She's been different all week, Mami. Have you noticed? She stopped getting mad when we talked about onii-san."
The memory of the sleepover crashed over them both. They remembered the taste. The salt. The heat. They remembered wanting to stay forever.
"She monopolized him," Sachie muttered darkly. "She used her 'Sister Privilege' to clear the field, and then she kept him all to herself. Look at her! She's practically radiating Rito-Energy!"
"Unfair..." Mami whispered, tears pricking the corners of her eyes. "I want Rito-Energy too. I feel... empty."
Before they could spiral further into their jealous despair, the classroom door slammed open again.
"EVERYONE! LISTEN UP!"
The shout silenced the room. The wrestling boys froze. The sticker-trading girls turned around.
Standing at the front of the class, breathing heavy, was Tanaka.
Tanaka was the ace of the soccer team. He had spiky hair, a perpetual tan from outdoor practice, and was widely considered the "Coolest Guy" in Grade 6. Usually, he was loud and confident. Today, he looked like he was marching to his execution.
His face was a deep, alarming shade of crimson. His hands were shaking violently. In his grip was a pristine white envelope, sealed with a heart sticker.
The class gasped.
"No way," a girl in the front row whispered.
"Is Tanaka-kun gonna...?"
"He's gonna do it! He's gonna confess!"
"To who? To who?"
"It's gotta be Yuuki-san. He's been staring at her all week!"
Tanaka marched down the aisle. Every step was heavy. He stopped directly in front of Mikan's desk.
Mikan didn't look up from her magazine immediately. She turned a page, looking at a spread about "Date Night Outfits".
"Yuuki-san!" Tanaka shouted, his voice cracking.
Mikan slowly lowered the magazine. She blinked her large gold brown eyes, looking at him with a calm, detached curiosity. "Yes, Tanaka-san?"
The contrast was brutal. Tanaka was sweating, vibrating with nerves, putting his soul on the line. Mikan looked as usual as ever.
"I... I have liked you for a long time!" Tanaka yelled, thrusting the letter forward. He bowed at a perfect ninety-degree angle. "You're smart! You're pretty! You're even good at cooking! Please... PLEASE GO OUT WITH ME!"
The classroom exploded into whispers.
"He said it!"
"He actually said it!"
"Tanaka has guts!"
"What will Yuuki-san say?"
Usually, this was the part where Mikan would have stood up, bowed politely, and let him down easy. She would have said something like, "I'm sorry, I have to take care of my brother and the house, I don't have time for dating." She would have used her responsibilities as a shield to hide her complex feelings.
But this was different. And Yuuki Mikan was no longer hiding. She had spent a week being practically drowned in affection by her brother, and a night being claimed by him.
She stared at the letter hovering inches from her nose. She didn't reach for it. She didn't react much.
Instead, she closed her magazine with a soft, decisive snap.
She rested her chin on her hand, leaning forward slightly. The movement was elegant, mature, a gesture she had unconsciously copied from books.
"I'm sorry, Tanaka-san," Mikan said. Her voice wasn't loud, but it cut through the whispers like a knife through butter. "I can't."
"W-Why?!" Tanaka stammered. "Is there someone else?"
Mikan smirked. Not a mean one, but rather a genuine, cheeky smirk.
"Yep," she replied. "I already have a boyfriend. And he's way, way cooler than any boy in this school."
The word hung in the air for a second, processing in the brains of thirty elementary schoolers.
Then, chaos erupted.
"EEEEEEEEH?!"
The shout blew the windows open.
"Yuuki-san has a boyfriend?!"
"Is he a middle-schooler? She's way too mature for elementary boys!"
"No way! He should at least be a high schooler! Or maybe a college student?!"
"He must be super rich!"
Tanaka turned grey. He looked like a statue that had been left out in the rain for a hundred years. He crumbled, literally sinking to his knees, the love letter slipping from his fingers and fluttering to the floor.
Mikan didn't seem to notice the chaos she had caused. She just hummed, picked up her magazine again, and went back to reading about summer dresses, a satisfied aura radiating from her like a force field.
Sachie and Mami sat frozen at their desks, their mouths hanging open.
"She said it," Mami whispered, her voice trembling. "She actually said it."
Sachie rubbed her face in frustration. "She's bragging. She is absolutely, one-hundred-percent bragging. She was taunting us, Mami-chan! She was basically saying, 'Look at me, I have something you don't!'"
Lunchtime arrived, but Sachie and Mami had no appetite for the cafeteria's curry rice. They had a mission.
They intercepted Mikan as she was heading to the roof, dragging her toward the secluded area behind the gymnasium. It was a spot usually reserved for secret trades of rare trading cards or illicit candy eating, but today it was the site of an interrogation.
The sun beat down on the dusty ground. Mikan stood with her back to the brick wall, sipping a juice box she had brought from home. She looked unbothered. In fact, she looked delighted to be cornered.
"Well?" Mikan asked, raising an eyebrow. "What is it? If you're going to ask about Tanaka-san, I already gave my answer."
"Forget Tanaka!" Sachie snapped, stepping forward. She placed her hands on her hips, trying to look intimidating, but she just looked desperate. "We know who your boyfriend is. We know it's onii-san!"
"We know what happened!" Mami added, her voice trembling. "You've been acting different all week! And today... today is too much! You're practically glowing in the dark!"
Mikan pulled the straw from her lips. A slow, cunning smile spread across her face.
"I don't know what you're talking about," Mikan teased. "Rito is just my brother. We just... bonded as family. We took baths together. He gave me massages. Is that a crime?"
"Liar!" Sachie stomped her foot. "You have the aura! The 'I-did-it-grown-up' aura! You definitely did the thing with him! You kept him all to yourself after the sleepover and you've been hiding it ever since!"
Mikan stared at them. She saw both hunger and jealousy in their eyes.
"Fine," Mikan sighed, though her eyes danced with mischief. "Since you guys are my best friends... and since you already saw and did some things during the sleepover..."
Mikan looked left, then right, ensuring the coast was clear.
"Look."
She reached down to the hem of her uniform blazer. Slowly, deliberately, she unbuttoned the bottom button. Then she lifted her white shirt, exposing her navel.
Sachie and Mami leaned in, their eyes popping out of their heads.
There, glowing faintly even in the daylight, woven into her skin just below her navel, was the Golden Heart Seal. The intricate pattern pulsed with a steady, golden rhythm, humming with alien energy.
"No way..." Sachie breathed.
"A Seal..." Mami whimpered, falling to her knees in the dust. She reached out a trembling finger. "It's real... It's warm."
"It's the proof of our bond," Mikan said, slapping Mami's hand away gently but smugly. She dropped her shirt and buttoned it back up with agonizing slowness. "For the last week, Rito has been spoiling me. Baths, kisses... everything I wanted. But last night... I told him that wasn't enough. I told him I wanted to be a wife."
She looked down at them, her expression softening into pity, but retaining its dominance.
"And he gave it to me. We are soul-bound. I am one of his wives. His exclusive partner."
She turned on her heel, her hair flipping dismissively.
"So, give up on trying to seduce him. He has plenty of wives to keep him busy."
Sachie gripped Mami's shoulder.
"I don't want to be a side character! I also want the Seal! I want to feel onii-san fill me up every time I want!"
Mami looked up, her eyes hardening. The shy girl who barely spoke in class was gone. In her place was a girl who had tasted heaven and refused to go back to purgatory.
"We have to fight back," Mami said quietly.
"Huh?"
"Mikan-chan thinks we are out of the picture because she has the Seal," Mami said, her voice gaining strength. "But Onii-san... Onii-san is weak to us. Remember the mirror room? Remember how much he cummed for us? He didn't look like he was 'just being nice'. He looked like he wanted to eat us."
Sachie's eyes lit up. A predatory grin spread across her face.
"You're right. His Royal Scepter doesn't lie! It twitched for us! It cried for us!"
"Operation Reclamation is a go," Sachie announced. "We aren't going there to play, Mami. We are going there to claim our territory."
*****
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