"Mr. Loner" Meets His Soon To Be "Ms. Stepsister"

"Ughh... What an annoying alarm clock you are..." I grumbled, slamming my hand down on the snooze button. It was the same annoying jingle every morning, my daily reality, even today, a weekend.

Now fully awake, thanks to the persistent alarm, I dragged myself out of bed to begin my routine: tidying the bed, straightening up the whole bedroom, brushing my teeth, a quick half-bath, and so on.

Once all that was done, I left my bedroom and headed downstairs for breakfast. But the moment I stepped into the living area, the kitchen lights were surprisingly on. I doubted Mom was home; she'd woken me up earlier to say she'd be out early. So why were the lights on? I pondered, a knot of confusion forming in my stomach.

Mustering my courage, I crept towards the kitchen. And there... it was a girl. A girl I didn't know at all. She was facing the counter, seemingly cutting something. But who the hell was she?! That was the pressing question right now. I had no idea who she was!

Not long after, she noticed me standing just beyond the kitchen entrance. She was startled, and the knife in her hand clattered onto the counter, thankfully.

"Who might you be?" I asked the girl, who was now just staring at me.

"Wha— Who are you?!" she stammered, then picked up the knife and pointed it at me. She seemed scared, but shouldn't "I" be the one scared?! This was my and my mom's home!

To avoid scaring the girl currently holding a dangerous knife, I decided to calm myself and introduce myself. "Well, I'm Kazuhiko Kazushi, a resident of this house. May I know who you might be?" I managed to say with feigned calmness, though deep down, I was terrified I might get killed in my own home.

Fortunately, the girl lowered the knife, placed it on the counter, and, with a relieved sigh, held her chest. "I'm Miku. Miku Shiina. You must be Hana-san's son, right? It's nice to meet you." As she said that, she bowed to me, as if formally greeting someone. But why?

Confused, I asked, "Why do you know my mom? And why are you here?"

She answered all my questions thoroughly, leaving no room for doubt. This girl... was my soon-to-be stepsister. Miku Shiina. One year younger than me, making her my soon-to-be younger sister. It seemed she had arrived earlier this morning with her father, and her father had taken my mom on a trip—a trip I was only just hearing about now!

Mom... why didn't you tell me you were planning to remarry? What is this? Some kind of filler episode in my life?! I held my head, showing my dismay. Well, she deserved it; I wasn't going to stop her. But as her son, shouldn't I have known about this?! Even the trip!

With that, Shii—no, Miku—was here to stay over. Mom and my soon-to-be stepfather apparently wanted us to get to know each other. But seriously? I was still trying to process it all.

"That's why, it's nice to meet you, Kazuhiko onii-san," she said, bowing to me again.

To show respect, I bowed too and replied, "Same here, Miku-san."

But then she burst out laughing. "HAHAHAHAH, why Miku-san? Miku is fine. I hope we get along." She was still laughing at my formality.

I scratched the back of my head. "Hehe... Sorry 'bout that. You see, I'm still processing all this, really. I didn't expect something like this, nor was I prepared. And yes, hopefully we get along."

"That's fine. And oh, Hana-san said you can't cook by yourself, so I'm cooking. Have a seat, and I'll be finishing this breakfast soon."

I nodded and sat down at the dining table. Miku seemed like she'd be a great stepsister. I'd always thought if I had a stepsister, I definitely wouldn't get along with her, but she was kind, even though we'd just met. But this was still so strange... I'd never heard anything about this from my mom.

With a surge of frustration, I screamed in my thoughts: Mommm!!!! Why didn't you tell me about this?!! I was kept in the dark until now... I'm definitely asking you a lot once you're back. Though I thought that, Miku then mentioned they wouldn't be back for at least three days. Damn it...

Not long after, Miku finished cooking, and there it was... A beautiful, tasty-looking breakfast. My mouth was watering.

"I hope you like it, Kazuhiko onii-san!" she said, looking directly into my eyes with a smile. She was quite cute. A shame she was my stepsister. Though I wasn't becoming a sis-con now, okay?!

She sat down in the chair opposite mine and clasped her hands. I clasped mine in response, and we said in unison, "Thank you for the food!"

Then, I dug into her food, and it was truly delicious! My mom's cooking was good too, but hers was definitely on another level.

But even at this point... I was still processing this entire situation, truly. Why did Mom have to hide this from me? Ughhh... I still felt so nervous. This was truly unforgivable, Mom...

And so, my weekend began with me and my soon-to-be stepsister living together. I'm definitely not becoming a sis-con, okay?! Definitely not.

Little did I know... this "filler episode" in my life would become an important part of it too.