I'm the Only One Who Doesn't Know My Sister is My "Stepsister" ~The Beautiful Twin Sisters Want to Seduce Their Oblivious Brother~ - 1

Chapter 1: I’m the Only One Who Doesn’t Know That My Sister Is Actually My Stepsister

ーーーーーーーーーーーーーーーーーーーー

“I’m going to marry Onii-chan!!”

“No! I’m the one who’s going to marry Onii!”

The high-pitched screams of two young girls echoed throughout a certain apartment room. The two of them were identical, equally adorable. These two young girls were the twin sisters of the Otaru family living in unit 604. Yuuri Otaru and Kairi Otaru. They were in their second grade of grade school and they had an older brother, Yuuto Otaru, who was a year older than them.

“Hey, hey! You two! Don’t fight! You need to be nice to each other, okay?”

Hearing his little sisters fighting, Yuuto rushed into the living room to calm them down. The two finally stopped their little scuffle for a bit.

“Why did you two fight?”

Yuto asked and the two girls pointed at each other at the same time.

“Because Kairi (Yuuri) said she’s going to marry Onii-chan!””

Hearing that, Yuuto sighed and placed his hands on their shoulders. 

“Good grief… Listen to me, you two. We’re related by blood. We can’t get married. Boys and girls who are related by blood can’t get married to each other.”

“”Huh?””

Yuuto tried to explain and the two sisters widened their eyes and gaped in surprise in unison. 

“That’s why… Yuuri, Kairi, you both should find someone much cooler and more handsome than me to marry.”

Both Yuuri and Kairi couldn’t understand what Yuuto was talking about. After all, in their eyes, Yuuto was a big brother they were proud of. He was smart, good at sports and good looking too. He was always praised by everyone. They had admired him since as far as they remembered and… They also loved him as a boy, not just as a big brother.

“Hey, hey~ Onii-chan,why can’t people get married if they’re related by blood?”

“Onii, do you not want to marry us?”

Yuuri and Kairi bombarded Yuuto with questions one after another. Yuuto was at a loss. He didn’t know the answer to that question either since he was only a third grader. And so, he skillfully dodged the question. 

“Be-Be-Because that’s the law! The law says so!”

The two sisters were devastated. They felt like a cloud was hanging over their head from that day on. However, the said cloud suddenly cleared seven years later. 

“Onee-chan, it’s already 12 o’clock. I will turn off the lights.”

“Wait, Kairi. I want to keep studying for a little bit more.”

Yuuri and Kairi were now in their third year of junior high school. Yuuri, being the honor student she was, was always on the top of her class while Kairi, who was more interested in nails and accessories, had dyed her hair blonde and embraced the gyaru style. The twin sisters had grown up in a completely opposite way, but they were both equally beautiful and had perfect figures that garnered the jealousy of other girls. Despite being a diligent honor student, Yuuri deliberately seduced those around her with her erotic voluptuous chest that could be seen even over her school uniform and her thick thighs. Contrary to her, Kairi, the number one gyaru in the school, always flaunted her large chest unabashedly. She often left a few buttons of her uniform undone and wore her uniform slovenly. 

Their faces were so beautiful and adorable that no one would bat an eye if they said they were in the entertainment business. They were known as ‘first love hunters’ among boys their age. Of course, they were extremely popular at the junior high school they currently attended. 

Yuuri was popular among the studious guys while Kairu was popular among the more rebellious boys. In fact, the school often went on a debate about which of the two was the top one beauty at their school. 

yes. Over the past seven years, the two had become famous as ‘the beautiful twin sisters’ in their neighborhood.

“No, but like, don’t you think you’re studying a bit too much, Onee-chan? Do you really want to get into the same high school as Onii that bad?”

“I-I’m not studying because of Onii-chan!!”

While filing her nails, Kairi sighed in exasperation as she watched Yuuri glued to her study desk even though it was already 12 o’clock. 

“In fact, you’re always getting red marks, Kairi. At this rate, you won’t be able to get into the same high school as Onii-chan, you know? Are you sure you’re fine with that?”

“So what? It’s not like I like him or anything. I’m not a brocon like you, Onee-chan.”

“Bro-Brocon?! Y-You’re wrong!! I-I told you it’s not like that!!”

Annoyed, Yuuri put down her mechanical pencil and stormed out of the room. 

“Wait? Where are you going, Onee-chan?”

“Ba-…. Bathroom.”

“Wait for me. I need to go to the toilet too.”

“Ugh…”

Yuuri and Kairi left their room and headed toward the bathroom together. 

“I’m going first, okay?”

“Huh? I’m the one who wanted to go to the bathroom first. Obviously, I’m the one who should go in first—”

They were arguing about who would go to the bathroom first while walking down the hallway when they noticed the light in the living room was still on.

“Isn’t it about time we tell the kids?”

(Is that Mother’s voice?)

The two sisters stealthily crept up to the door of the living room and pressed their ears against it.

“But, isn’t it better if they don’t know about it?”

(And Father’s voice too?)

This was the night where they learned the truth about their family. 

“I think it’s best if we don’t let them know that… Yuuri and Kairi aren’t actually related to Yuuto by blood.”

(Huh…?)

The two sisters exchanged shocked glances before they decided to return to their room. The shocking truth was so surprising that the urge to use the bathroom had disappeared from their system. 

And the said truth… Became their greatest desire.

“Onii and…”

“We…”

“”Are step-siblings?!””

Meanwhile, Yuuto, who was still oblivious to this truth, was…

“Woohoo! This new VTuber is super cuteeee! I’m going to throw all my money to send her Super Chat so she will notice meeeee!~”

He had turned into the typical unpopular guy, spending his time and money to send Super Chat to VTuber.

ーーーーーーーーーーーーーーーーーーーー