My Girlfriend Cheated on Me for My Best Friend, But I Found True Love in His Sister - Chapter 01: The Worst Day of My Life

Chapter 01: The Worst Day of My Life

I thought he was my best friend, but he stole my girlfriend.

Well, “stole” might be a bit of an assumption.

I happened to see them. My friend and my girlfriend leaving a hotel after work.

They were close, holding hands like lovers. My girlfriend was calling my friend’s name with a voice I’d never heard before, and my friend was stealing kisses from her lips.

It was obviously a scene of infidelity, so much that I wanted to doubt if it was a dream or something.

I don’t know how far they had gone, and I didn’t want to know exactly.

But one thing was certain: my girlfriend was cheating on me.

And the person she was cheating with was my best friend.

They were kissing… even though I had never done that with her…

“Hah.”

I let out a heavy sigh.

Along with my breath, my vitality also seemed to leave me.

While crouching in the corner of my room, I felt the urge to disappear.

I never thought I would be cheated on.

My first girlfriend, who I had been in love with since childhood, was my childhood friend… With his support, we finally became a couple. I thought my feelings had been fulfilled, and we could spend a happy youth together.

But… What is this?

It’s only been three weeks since we started dating.

It’s not like we were in a rut or anything. I thought we were smoothly progressing as lovers. But it seems that was only my impression.

“I had never seen that expression on her face before…”

I muttered absentmindedly, looking up at the white ceiling. 

Perhaps, had they been dating before she started dating me?

Was our relationship just a game or born out of sympathy? Or was it just to make fun of me? 

I couldn’t come to a conclusion no matter how much I thought about it. 

Whatever the reason, it was not a pleasant feeling.

I had been toyed with. That fact would never change no matter what.

If my childhood friend and my best friend were just hanging out innocently, I could have sincerely wished them happiness, suppressing my jealous feelings. 

But… this was just too much.

“That’s just terrible,” I said, burying my face in my hands while sitting cross-legged.

I no longer had the confidence to face either of them. I couldn’t speak to them properly. Our relationship was over.

… It was the worst day of my life.

—Ding Dong—

It was a time when I was shrouded in a gloomy, purplish aura. The doorbell rang.

I was currently living alone. Therefore, I was the only one who could respond to the visitor. But… I was too lazy to stand up.

—Ding Dong—

I didn’t know who it was, but I’m sorry. I’ll have to pretend like no one’s home.

—Ding Dong—

…

—Ding Dong—

—Ding Dong—

—Ding Dong—

—Ding Dong—

“Shush, so persistent…”

The intercom kept ringing periodically.

I had planned to pretend I wasn’t home, but it was too persistent.

I reluctantly got up and headed to the front door.

With a creak, I opened the front door. And there, standing before me was…

“Rinka-chan?”

She had light, chestnut-colored hair pulled to the left side in a side ponytail. Her facial features were well-defined and her skin was so white it was almost worrying.

She was a bit smaller than average in height, but her chest seemed to have received all the nutrients, giving her an overly feminine figure.

She was a year younger than me and currently a first-year high school student. And, what’s more, she was the younger sister of my former best friend.

“Good evening, Senpai. You look even more gloomy than usual.”

As soon as she saw my face, she muttered a light complaint.

My mood was already low, and her words usually wouldn’t bother me, but they hit differently this time.

“Can I ask you to leave?”

“I don’t want to. I can’t leave you alone like this, Senpai.”

“Huh?”

“For now, can I come inside? It’s so cold out here.”

It was already November. At this time of day, when the sky was getting dark, the cold was enough to make you feel numb.

In fact, Rinka’s hands were shaking and red. I didn’t know the reason for her visit, but I decided to invite her into my room for the time being.

★

Across the low table, Rinka and I face each other.

“Senpai, I wanted warm lemon tea.”

“I don’t have anything like that. If you don’t want to drink what I have, you don’t have to.”

“No, thank you. Since you went to the trouble of making it.”

Taking the glass of barley tea from me, she took a sip.

After quenching my thirst, I decided to get straight to the point of why she came.

“So, do you have any business with me at this hour?”

“Not exactly, but I was worried about how you’re doing, Senpai.”

“Worried?”

“Yes. You tend to get caught up in your own thoughts and worry by yourself. I was afraid you’d be down and disappear without talking to anyone.”

Her words struck a chord with me. I was deeply depressed after being cheated on.

Did she see the same cheating scene as me?

“Did you also see it, Rinka-chan?”

“I saw you walking with your head down. After that, I saw your girlfriend and my brother having an affair…”

“I see…”

“That’s just… It’s really unbelievable, isn’t it?”

Rinka muttered under her breath, clenching her skirt so hard that wrinkles appeared.

She looked down, suppressing her frustration.

I was dragged down by it, and I hung my head with a gloomy expression. 

I couldn’t bear it. The air was heavy like at a funeral.

“Senpai…”

“Hmm?”

“Do you hate your girlfriend and my brother?”

“… Well, I know it’s not a good feeling, but yes, I do have those emotions.”

“I’m glad.” 

Rinka’s dark expression turned into a bright smile. I tilted my head, not understanding her intention.

“Glad about what?”

“I’m glad you’re hating them here. If you started saying you wanted them to be happy or anything like that, I’d think you were a saint.”

She stared directly into my eyes and wrapped her hands around mine, which were weakly placed on the table.

“Senpai. You don’t stay to get beat up like this, right?”

“… I don’t want to. But now that it’s happened, there’s nothing I can do about it.”

“You can do something. I’m here for you. Let’s fight back!”

“How are we going to fight back?”

I raised a question mark, not understanding what she meant. 

Then, Rinka tightened her grip on my hand.

“I’ll be Senpai’s affair partner. Let’s teach those two the pain of being cheated on.”