"...Huh!?!??!?!"
Nino stood frozen, gaping at Rin's sudden confession. Her lip twitched as she stared at him with sheer bewilderment.
"You philandering pervert! That time was just an accident! Do you think I'm some cliché shoujo manga heroine who falls in love just because she got kissed!? Besides, confessing to your girlfriend's sister? Have you lost your mind?"
Nino's reaction was exactly what Rin expected. He gave her a teasing, half-smile. "If Ichika wasn't my girlfriend, I wouldn't even bother confessing to you. Most tsunderes are thirty percent 'tsun' and seventy percent 'dere.' You're at least ninety percent 'tsun'—I haven't seen a single drop of sweetness yet."
"What did you say!? Say that again!" Nino's face flushed a deep crimson instantly. She lunged forward, grabbing Rin by his collar.
His words stung. He made it sound like she was just an accessory to Ichika. How was she inferior? He only confessed because of Ichika? And what kind of twisted logic was it to hit on a girlfriend's sister?
"Tsk, tsk... you think I actually like your personality? If you were just a random sister, I wouldn't care. But you and Ichika are identical twins. Oh wait, you failed biology, so you probably don't know that identical twins come from the same—actually, never mind, you wouldn't understand the science anyway."
"...."
Nino was vibrating with rage, her shoulders shaking. She looked ready to deck him at any second.
"You and Ichika look exactly the same. You can even impersonate her perfectly... Just thinking about a body identical to Ichika's being bared before another man—or worse, you dressing up as Ichika for some other boyfriend in the future—makes me sick to my stomach."
"So... that's why you confessed!?" Nino was floored by his audacity. Not only was he a pig, but he was a pig who explained his disgusting, possessive logic with total confidence!
"Exactly. And the same goes for Miku, Yotsuba, and Itsuki."
Rin struggled to keep a straight face as Nino's temper reached its boiling point. He decided it was time to change tactics before she actually took a swing.
"And besides..." Rin's tone softened, "Beyond my own possessiveness, Ichika often tells me how guilty she feels. She says you all promised to stay together forever, but now she feels like she's the one who ran off and left you behind."
"!!!!"
"You hated me because you thought I stole Ichika from you, right? You thought I was breaking up your family." Rin leaned in. "But I'm not here to break up this home; I'm here to join it. If I can make all of you fall for me, then the five of you can stay together forever. No one gets left behind."
Nino's grip on his collar loosened. She stared at him, her mind racing. She didn't even know how to begin insulting him. The sheer, unadulterated gall of this man!
"You... you... shameless bastard! You're just a skirt-chaser looking for excuses!"
"Maybe. All men are skirt-chasers. No man could look at five beautiful, identical sisters and not want them all."
"...."
Nino opened her mouth but found no words. Despite his shamelessness, his words hit her right where it mattered. She was the one most obsessed with the sisters staying together. After her talk with her father tonight, she had already begun to accept Rin as Ichika's boyfriend.
But he didn't want just one; he wanted the whole set. It was greedy, yes, but to a girl terrified of her sisters drifting apart after graduation, Rin's "solution" was strangely tempting. They wouldn't have to separate to start their own families; they would be the family.
"Fine. Since you're so ambitious, I'll give you a chance."
Nino leaned back into the sofa, crossing her arms. Her school uniform tightened over her large breasts as she crossed her legs, a playful smirk finally appearing on her lips. She wasn't "in love" with him yet, but if Ichika and Miku were already on board, she didn't mind giving him a shot. Plus, since Miku liked him, this was a perfect opportunity to tease her.
"I can help you with Yotsuba and Itsuki. But first, you have to do the most basic, fundamental thing."
"And what's that?"
"Simple. You have to be able to tell us apart when we're dressed exactly the same. Easy, right? If you want to own us, recognizing who is who is the bare minimum. If you can't even do that, forget the rest!"
"Deal. If that's all, I'll head home."
"Wait! Come into the bedroom with me for a second."
"Oh?" Rin raised an eyebrow. Was she inviting him for a "test drive"?
Nino's face reddened as she caught his suggestive look. "W-what are you thinking!? I'm not asking you to stay the night... I just want to take a photo!"
She dragged Rin over to the floor-to-ceiling window. She looped her arm through his, holding her phone up to capture them against the backdrop of the city lights. She flashed a brilliant, triumphant smile.
Click!
As soon as the photo was taken, Nino smirked and opened her chat with Miku, hitting "Send."
Ichika: [How did the talk go?]
Rin: [Not bad. I told them to work harder so they pass two subjects next time.]
Ichika: [How do you do it? Tell your big sister your secrets~]
Even though Ichika was younger than Rin, she loved roleplaying as the "older sister" to tease him, claiming it was for her acting practice. Miku had told Ichika that Rin kissed her, but she hadn't mentioned that the four of them had dressed as Ichika to "seduce" him at his house yet.
Rin: [It's a secret.]
Rin: [You'll find out eventually.]
Ichika: [So mean. Well, I'll leave my little sisters in your hands~]
In Miku's mind, Rin's tutoring-kisses were a way to satisfy Ichika's cuckold fetish. However, since they had initiated the "seduction" without Ichika's explicit permission for that specific event, Miku felt a sense of urgency. If the girlfriend gives it to you, it's a gift; if you take it behind her back, it's theft. She needed to bridge that gap.