"..."
Rin knew Moeha was a "pink on the outside, black on the inside" type, but he hadn't expected her to be this dark... Beneath that innocent facade lay some seriously heavy tastes!
"For example, Kaguya-chan. Don't you want to lock her in the basement forever and 'love' her thoroughly from head to toe? There are lots of cute girls in my class, too. Do you want me to introduce them?"
"Lock her in your head." Rin flicked Moeha's forehead. Locking a rich heiress in a basement was a classic manga trope, but manga was manga and reality was reality.
He was down for roleplay, but Moeha looked like she actually wanted to try the real deal.
"How about you try being locked up first to see how it feels?"
"I'd love to! Ow!" Moeha stuck her tongue out after being flicked. Before she could continue, Chika grabbed her shoulders and pulled her away from Rin, looking at him suspiciously.
"What are you two doing in here!?"
"Nothing, Sis," Moeha blinked. "Oh, by the way, you mentioned teaching me 'adult knowledge' earlier..."
"Uh... adult knowledge is something you learn on your own when you're older." Chika looked away, changing the subject. She glanced around and whispered mysteriously, "What do you think of this place? I'll tell you a secret, don't tell anyone! This place is actually haunted!"
"Doesn't matter. They're so full of 'vital energy' they have nothing to fear from ghosts!" Rin joked.
"What do you mean 'vital energy'!?" Chika puffed her cheeks and playfully punched Rin several times.
"???" Moeha looked at her sister, who had suddenly turned red. Why did she blush at the mention of "vital energy"? Was it some perverted code word?
Moeha didn't care. She wasn't going to let the "education" topic slide just because the basement deal was on hold.
"Sis, you promised to teach me." Moeha tugged on Chika's sleeve, looking like a pathetic, abandoned puppy.
"That... the teachers at school will cover it in health and hygiene class." Chika tried to deflect again. "Wait, you have those classes now. Didn't the teacher tell you anything?"
"They did..." Moeha lowered her eyes. "But... but there's a lot the teachers don't cover. For example... 'self-pleasure.' My classmates were talking about it after class, and I... I didn't know anything. I felt so left out..."
"Guh!!!" Seeing Moeha look so sad, Chika felt a pang of guilt. She didn't know if Moeha's classmates actually talked about that, but she could imagine the pain of being unable to join a conversation with friends.
"I... I get it. I'll teach you when we get home!"
Moeha wasn't satisfied with just Chika. "Sis only knows about the girl's side of things. Big Brother, you have to teach me too..."
"I don't mind." Rin smiled at Chika. "After all, girls should be well-informed so they don't get tricked by bad men."
"Exactly," Kaguya added, entering the room. "Knowing more means you won't lose your 'most precious thing' in a state of confusion."
You guys are the worst of the 'bad men'! Chika glared at Rin and Kaguya, but then she felt helpless... Rin was right. She was the perfect example. Back then, even though she knew she couldn't get pregnant from what they were doing, she didn't say anything and let him "prove" it to her in all sorts of ways! She had given him everything because she was clueless!
Teaching Moeha herself was better than letting her go to him in secret, where she'd surely be devoured.
"I... I'll be the one to teach her. You... you can be the teaching aid. No talking!"
"No problem. For Moeha's sake, I shall make this small sacrifice."
After the quick tour, Rin, Kaguya, and Hayasaka followed the sisters into their home next door. As soon as they entered the foyer, Rin noticed a plethora of bizarre decorations. Antique-looking wooden dolls, feathers stained with blood... they wouldn't look out of place in a high-end haunted house.
"These are my eldest sister's collections. The house is full of them, even the basement... Big Brother, better not touch them. It would be bad if you got cursed. Like, being trapped in a room where you can't leave unless you fall in love or something."
"There's no such thing as a curse like that!" Chika blurted out. "These are just souvenirs! No curses!"
Leading them to the living room, Chika looked at her sister with a serious expression.
"Just this once, okay? Ask whatever you want to know."
"Um... I want to know what 'self-pleasure' is."
Not just Moeha, but Rin, Kaguya, and Hayasaka all focused on Chika. Kaguya even pointed her camera at her.
"Self-pleasure is... it's... it's..." Chika whispered, her face beet red. "It's when a girl does the things used for making babies to herself to feel good..."
"Eh? Isn't making babies something you only do with a boy you like? Can you really make yourself feel good alone?"
Even though she knew everything, Moeha maintained her mask of innocent curiosity.
"That's right," Kaguya explained with a smile, still holding the camera. "While making babies is very pleasurable, doing it with a boy carries the risk of actually getting pregnant. The teacher probably mentioned condoms, but there's always a risk. If you use your hands or small toys, there's no problem... Chika, you should have some in your room, right?"
"I do NOT!" Chika screamed before glaring at Moeha. "Anyway... if you want to feel good, just do it yourself. Never, ever go looking for a boy!"
Moeha nodded as if she understood. "Was Sis doing that in her room last night when she was making those loud, happy sounds?"
"Pfft..." Rin and Hayasaka both covered their mouths to stop from laughing. Even Kaguya's smile twitched.
"Th-that's right! You were eavesdropping!?"
"Ehh... it's just because you were so loud, Sis. Ah!" Moeha acted as if she just remembered something. Rin could see the mischief in her eyes. "Last night, while Sis was pleasuring herself, I think she was screaming Big Brother's name."
"GUH!!!!!" Chika's face turned an impossible shade of red.
"So that's how it is. No wonder you haven't come to see me lately, Chika. You were busy thinking about him and rubbing yourself in secret. Even though you knew I liked him, you were still fantasizing about him..." Kaguya and Moeha shared a look of perfect synchronization. Kaguya's joy was uncontainable.
"What a filthy sow."
"I... I am NOT a sow!"
"Hmph! No wonder you told me to stay away from him. You like him yourself!" Moeha puffed her cheeks in mock anger. "Making babies is for people who like each other. Since you like him, Sis, show me how you make babies with him!"
"EHHHHHHH!????"
A panicked Chika looked to Kaguya and Rin for help. Doing it in private was one thing, but doing it in front of Moeha... No, no, no, NO!!!!!
"Ahem..." Rin cleared his throat. "That sort of thing is only for when two people are alone."
Phew... I thought he'd take the opportunity to push for more. Chika sighed in relief and quickly agreed. "Exactly! You only do that later when you find a man you truly love and want to have babies with."
"Your sister is right," Rin nodded, before shifting gears. "So for now, just stick to self-pleasure. If you don't know how to do it, Chika can give you a demonstration."
To get someone to agree to open a window, you first suggest tearing down the roof. If Rin had asked Chika to demonstrate masturbation directly, she would have refused. But since Moeha asked to see them have sex, Chika would now settle for the "lesser" embarrassment of a solo performance.
"????" Chika's gratitude evaporated instantly.
But... doing it herself was better than being devoured in front of Moeha.
"Fine, fine! I'll show you, okay!?"