Disclaimer: I do not own Vocaloid.

The Kagamine Twins, consisting of Rin and Len. The two were tight—supporting each other through thick and thin. Neither one of them turned their back on the other or left them to fall. Yes, both teenagers had a strong love for each other; but there's the key word—had. Before the event, they never held a grudge against their twin. For any reason whatsoever Rin forgave Len for every single mistake and he did the same. Of course, no one's perfect. We all make mistakes, right? Right. So what made this one stand out from all the rest?

"Rin, Rin!" Len called out from his room behind the closed door that engraved his name. His twin came in a second later with questioning cerulean eyes.

"Yes?" She asked as she still held the doorknob with one foot in the room and the other out. Rin sat on his bed with crossed legs, a hand on the mouse of his laptop while the second behind his head, and eyes glancing at his sister every millisecond. Rin stepped entirely on the carpet then shut the door. Clasping her soft hands in front of her legs she skidded closer to her brother.

He decided to stare at her completely then placed both of his hands on his lap. "Remember a week ago when you sang for me during my birthday? And I recorded it?" He looked at his sister with nervous glints in his eyes. Rin caught it and squeezed her fingers.

"What about it?"

She was beginning to have her accusations; through it would be unfair to blame him for something she doesn't know is true.

"I uploaded it on the internet."

There it was, the truth she refused to recognize and gave into it as a lie.

"...Are there any comments?"

"Just a few," Len assured. "But they're not great. I tried to remove them though!" Tried. He tried—doesn't that count? Rin didn't think so, but for her twin's sake, she believed it.

"Don't worry, I'm not mad. I know my singing isn't the best in the world -"

"I think it is." Len chimed thoughtfully. At this, Rin's expression changed; she knew brother would try to make it up to her—even in the slightest action he did. Len felt bad about not asking his sister for permission to upload the video.

That's one mistake.

Len and Rin stood outside the door of a restaurant they reserved themselves in. Rin remembered something as time went by and asked her brother for her phone. He nodded his head and reached his hand inside his jacket pocket; it was chilly outside so the twins wore over-sized sweaters. Len grabbed his sister's phone and brought it out. As he was reaching to give it to her, he suddenly dropped the phone. Rin gasped slightly at the sight of broken pieces on the sidewalk. Len immediately bent down and collected the parts. He stood back up and sheepishly handed it to her.

"I'm sorry," His head hung down in shame. After a few seconds he noticed Rin wasn't talking. His eyes looked up at her with curiosity. "Rin?"

"It's okay." She whispered.

"You don't look okay," Len responded as he stood up straight. "Is there something you want to tell me?"

"I was expecting a call from Miku, is all."

"Was it important?"

Rin clenched her fists and spoke a bit more louder. "She was going to tutor me, Len. You know that there's a test in math and to pass the class you need to pass the test."

"I didn't know you had trouble in math!" He exclaimed. "Why didn't you tell me? I can tutor you!"

Rin's eyes widened; not because of the offer, but because of how idiotic she realized she has been. Len could have tutored her from the start, she just needed to ask him. He was her brother, after all. She could count on him for anything.

"Thank you, Len...I'm sorry."

"Why?" He asked, a bit confused.

"For not realizing that you were right in front of me. I completely ignored you." She admitted guiltily. Len smiled at her and put an arm around her shoulder. He rubbed her head and laughed—his sister was so oblivious at times.

Another mistake.

"I'm sorry, I can't accept it." Meiko told Len as she gave him back his love letter. Len softly took it and stared at her.

"W-Why?"

"Isn't it obvious? I'm older than you. It won't work out, Len..." With that, Meiko turned around and left. Len was left there with a broken heart and saddened mood.

Why did I have to fall for her? Why did my friends convince me to like her? Why did I agree?

From afar, Rin was watching with furrowed eyebrows. Len noticed and immediately gave her confused look. It read 'why are you there?' Rin came out of the shadows and walked up to him.

"Rin, what were you doing there? Did you see what happened?"

"I did, I'm sorry. I was...spying on you. I noticed you and Meiko and didn't want to interrupt, then I saw you confess and I thought I'd watch. Ah, that doesn't sound right. Sorry!"

"It's alright. I'm glad you're here, though. We should go home already," He gave her a weak smile and began to turn around. Rin called out his name, causing him to stop in his tracks. "What is it?"

"I..." It was beginning to get to her. "I set this up. I purposely wanted you to fall for her...and get rejected..."

"What?! Rin!" He faced her completely and crushed the note in his hand. His sister took a step back and began to defend herself.

"I said I was sorry, Len. Please don't get mad..."

"What was your purpose?"

She didn't dare answer. She wouldn't risk it—but it was too late. A group of guys twice their age walked up in front Len and picked him up. Startled, he began to kick them and shout.

"Let go of me! What's going on?!"

"Please forgive me!" After the golden-haired girl said that she ran off in the opposite direction.

"Wait! Rin!" His twin sister faded from his sight. His screams weren't heard, his yelps were silent, his thoughts were gone. The older boys beat Len.

Why...why did she betray me?

They were the Kagamine Twins, the ones who stuck with each other through everything. So why now? Why did Rin choose to leave Len at a horrible time like this?

At this moment, Rin was sitting in front of her fire-place, watching the money she earned burn in the fire. Those filthy papers of green were fading in the ashes in front of her eyes. She felt as if she didn't deserve it; and she was right. It was a wrong decision, to be greedy and sacrifice the one she loved dearly, for money.

Such a terrible decision.

She hated herself for it. Rin Kagamine wished to take back what she did with all her heart. This was something she would have to live with for the rest of her life. It'll haunt her until the end of time—was the thought that ran through her regretful mind. A few minutes later, she heard the click of the doorknob lock. She whirled around and saw her torn brother.

A pang of hurt struck her heart. He passed by without looking at her, although she could feel and see the disgust in his eyes. The aura in the room filled with resent and guilt. Rin wanted to burst out crying; this ate her alive. Len Kagamine didn't care though, it was something unforgivable.

What a mistake they've both done.