Osomatsu-san Oneshots

Explanation and Feelings (Karamatsu x Sister! reader)

"Well. Explain yourselves." Osomatsu says as Karamatsu and I were sitting on our knees in front of our brothers. I had my hoodie and underwear back on while Karamatsu had only his bottoms on. I look up and gulp "it's my fault." I say and Osomatsu looked at me. Keep in mind he had on his serious, emotionless face. "Really?" He asks with a raised eyebrow. I nod "I'm the reason we are together to begin with...because I couldn't lie about my feelings anymore."

Todomatsu hums "So you're dating then? How long has that been going on?" He asks and I shy away "..for a year. You were never suspicious because my usual affection and behavior for her didn't really change..we would just act more like a couple when we were alone." Karamatsu answers for me and Todomatsu hums with a nod. "Does anyone else know?" Jyushimatsu asks and I nod

"Our parents. They were surprisingly okay with it." I say and he nods. Osomatsu sighs before smiling. "You know what? I can't be mad." He says causing Karamatsu and I look up at him surprised. "What? Really?" I ask and Osomatsu nods

"yeah, for some reason I'm not really mad...I'm not even surprised actually. Y/n, you were always around Karamatsu 24/7, still are, and you always have a smile on your face when you're around him. As for you Karamatsu, well I could see why you'd like her." He explained "what do you guys think?" Todomatsu shrugs

"it's fine with me..I just wish I hadn't walked into that situation." They all nod at that statement making the both of us blush. "You know that I'm fine with it." Choromatsu says with that triangular smile and I nod. Jyushimatsu agreed and Ichimatsu stayed silent for a second before nodding "it's fine with me." Ichimatsu says in that tired tone.

"Maybe you should've just told us to begin with." Todomatsu says with a small laugh. I blush and laugh shyly before hugging Karamatsu's arm. "Yeah..I guess we should have." I say softly and snuggle up to Karamatsu. Who in a way was still my brother but I preferred to think of him as my boyfriend now. I was happy that we could act affectionate even if our family was home.

"Hey how about we go to Chibita's!" Jyushimatsu suggests and everyone nods. "Let's wait for this two to change." Osomatsu says and we nod with blush on our faces. So we quickly changed into fresh clothes and all of us head out for something to eat.
....

-3rd person-

It was midnight and the matsuno family was asleep. Well except one of the brothers. He was awake and sitting up staring at the sleeping couple. A couple whose love made him sick with jealousy. Not because Karamatsu was the first to have a relationship. No. It was because Karamatsu had chosen to date y/n.

He cared a lot about her. He loved her. He chose to wait before saying anything and now he regrets not confessing to y/n. He lost the girl he loved and cared about to his brother. To Karamatsu. It was him he was jealous of.

It was Karamatsu who got to have a happy relationship with y/n.

Karamatsu was hers and y/n was his.

The brother got up and left the room with a huff. He went downstairs to look in the mirror. "Why...Why did I wait..now I'll never...I'll never.." He says before groaning and punching the wall. "Damn it." He muttered shakily before placing his back against the wall and sliding down into a sitting fetal position, crying into his folded arms.

He stopped for a second "n-no...maybe if I" he trailed off and nods

"I'll tell her. Even if she is with him now. I'll tell her how I feel." He says with a small, almost hopeful, smile.

Deep down he had hopes that if he told y/n and showed he could be better.

Then maybe, just maybe

Y/n could become his instead.

To be continued in part 4; I'm so sorry