I'm the Only One Who Doesn't Know My Sister is My "Stepsister" ~The Beautiful Twin Sisters Want to Seduce Their Oblivious Brother~ - 8

Chapter 8: It’s Time to Study

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–The following day after school—

The day after I promised to help Kairi with her studies, we officially began her study sessions in earnest. It was already September and a part of me couldn’t help but to wonder if Kairi could catch up with everything she needed to learn in the few months we had left. After all, Kairi had never paid any attention in school. Regardless, I knew I had to support her enthusiasm. Better be late than never after all. 

“I’m home.”

When I returned to our apartment unit, I peeked into the living room. Sure enough, Kairi had already arrived home before me. She was quietly sitting at the table, seemingly studying. 

“Onii! You’re late!”

“Sorry, sorry. I had things to do at the bookstore.”

Just like yesterday, Kairi was wearing a loose-fitting thin T-shirt that revealed her large chest and a pair of tight hot pants. Being the typical gyaru, Kairi’s skin was slightly tanned. Her cleavage and her thick thighs were hard to ignore. It was hard to believe that she was just a junior high school student with how impressive her figure was. But, well, that was not important right now. 

“Let’s start the study session.”

I placed my bag on the floor and rolled up my uniform sleeves as I took a seat across from Kairi.

“Kairi, take a look at this.”

“This?”

I opened my bag and pulled out a few study materials. Then, I spread them all on the table.

“Since your academic ability is practically at zero and we only have a few months left, I bought you the latest versions of the textbooks I used when I was preparing for the entrance exams.”

“My academic ability is zero?! Onii! You’re being too cruel!!”

I told Dad yesterday that Kairi was aiming to get into Shugakuin High School, the same school I was attending at. So he gave me some money to buy more study materials. Hence why I stopped by the bookstore after school today to pick up a few reference books that seemed good. I was always running out of money, so a part of me wanted to take some money and consider it as my teaching fee, but I held back. I reminded myself that I was Kairi’s older brother and I had to act as such. 

“Alright. Let’s start with math. We will begin by reviewing the parts I taught you yesterday.”

“O-Okay. But before that.. Onii, do you want some snacks?”

Kairi offered me a box of chocolate snacks from the table. It was a box of Chocorooms. 

“Snacks? You’re being awfully thoughtful for once… But you know, I’m more of the bamboo shoots type rather than the mushroom type.”

“If you’re going to complain, then I won’t give it to you.”

“I-I will take it! Thanks, Kairi.”

I accepted the box from Kairi and took a small bite. Hmm, the ratio of chocolate to biscuit is just right—

“No!! This is not what we should be doing now! We need to study!”

“Onii, feed me one too.”

“…What?”

“I want some too. Hurry up and give me one.”

Kairi said as she opened her mouth wide.

“Aaah~”

She was opening her mouth in an exaggerated way. She had been acting strange since yesterday and today as well. 

Has she gone mad…?

But well, Kairi always acted like this since she was little. She always sent a subtle sign when she wanted to be spoiled. She was never frank with me. No,no,no! There was no way she still acted like that given her age. I didn’t know what was going on, but we really needed to get back to studying soon.

There’s no helping it I guess.

I picked up one chocolate biscuit and extended my hand to her and—

“Hamph!”

The moment I extended my hand toward her, Kairi snapped at the snack like a fish going after bait, biting not just the chocolate but my finger too.

“Yo-Yo-Yo-You!!”

Kairi made a squelching sound as she started sucking on my finger. She licked the tip of my finger lewdly with her rough tongue. Her face and my finger in her mouth… This view was too erotic.

No, wait! Why am I letting my little sister do this to me?

“…Mmpha. Did it feel good?”

“Wha-What the hell are you doing?!”

“Well, I was a bit upset because you mocked me at the family restaurant yesterday, so I studied some things! It was sexy, right? Erotic, right?”

“If you have the time to study that kind of thing, then you better use that time to memorize at least one English word!!”

“What’s the matter, Onii? Are you feeling embarrassed? Are you getting all flustered because your little sister just sucked your finger? Heh. What a lame cherry boy.”

Knowing Kairi’s level of intelligence, I doubt she even understood the meaning of ‘cherry boy’. She probably just used it for the sake of it.

“I’m going to wash my hands.”

“The heck?! It was a reward!!”

“How is that a reward?”

“….I-I heard guys like it when girls do stuff like that…..”

Kairi pouted as she twirled a strand of her blonde hair around her finger. 

“This innocent gyaru…”

I muttered as I washed my hands in the kitchen sink. Truth to be told, I was a bit surprised to know how pure Kairi was. I had imagined that she would have more experience with guys since she was a gyaru. I guess I was wrong.

When I returned to the table, Kairi was flipping through the pages of the textbooks I had bought. She looked genuinely interested in studying the textbook. 

“By the way, Kairi, don’t you have any crush in your school? You know, since you’re a gyaru so maybe you like a fellow yankee or something?”

“I don’t have any yankee friends, but… I do have someone I like.”

“Oooh…”

I knew it. Kairi had a crush. Well, it made sense. She was at that age after all. 

“I-I’m actually trying to study for the sake of the guy I like!!”

Kairi said, looking flustered as she gripped the mechanical pencil on her hand. 

Ahhh, I see.

I was curious why she suddenly said she wanted to go to the same school as me, but it turned out she wanted to get into the same high school as the guy she liked. If the guy she liked was coming to my high school, then that guy must be pretty smart. A relationship between a top student and a gyaru. Heh. Definitely worth rooting for. 

“Alright. Let’s do our best for the sake of the guy you like!”

“Ughhhh!!!!”

But for some reason, Kairi was glaring vehemently at me. 

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