(Y/N)'s POV

I live in a big mansion, with my parents and older sister. My older sister and I......didn't get along very well growing up. But since the mansion is very big, we're able to avoid each other. But....every time our parents go out, she acts like she's the boss of me. Like once she was walking through the hall when she shouted "(Y/N)!!! CLEAN THE F***** HALLWAY B****". Also she brings her boyfriend Tsukishima, or Kei. (Omg my heart just melted mentioning his real name 😍😍😍😍). She always makes out with him, not the literal, the kissing and all. Not the body to body stuff. But, to be honest, he's good looking. Sometimes I catch him staring at me and I feel my heart beat fast. Then an idea popped in my head. I'll make my sister jealous by taking her man. That'll teach her a lesson to never mess with me again. So I just have to wait for the right time. I spied to see when the perfect time was. When suddenly, "Oh my god, Yui is such a crying mess right now" (S/N) (Sister's name) said. "Should I really care?" Tsukishima responded. Ahh how I love the saltiness that surrounds him. "Of course you should! She's my friend! Silly!" She said. "Well what's wrong with her?" He asked, "She just found out her boyfriend was cheating on her" She answered. "Sorry babe but I have to go comfort her, you can hang out near the pool if you want?" "Okay" Tsukishima said bluntly "And?" (S/N) said "I love you bye" He finished. "Good!" She said and kissed his cheek. I heard the sound of her bed squeaking signifying she was going to leave. Oh no. I was in front of her door, I quickly ran to the closest door, but then I realised that it was her bag and shoes closet. I panicked and I heard the room door open, then the closet door. The lights weren't turned on yet so I ducked under her and ran. ~Few Minutes Later~ I was getting something's when I ran into someone. I fell back and quickly got up, not bothering the see who it was, even though I knew who it was. I quickly ran away into my room and took deep breaths

Tsukki's POV

I was walking through the mansion, exploring when someone ran into me. I looked to see her sister and I had to admit she was a lot more prettier, and hotter. She quickly ran away and I looked at her, "Cute" I mumbled before continuing my search. I found some swim wear so I wore it and went out to their pool.....which was pretty big. I sat down on one of those chairs, closed my eyes and just relaxed. I stayed like that for a few minutes until I heard footsteps, followed by a splash. I opened my eyes and sat up to see her again, wearing a hot swimsuit, which showed off most of her body. "Oh, sorry...if I disturbed you" She said, blushing slightly. "I-It's okay" I stuttered and felt my face heat up. I stood up and sat near the ledge of the pool. We talked and laughed and we got in the pool together. I felt myself lean towards her and felt our lips connect. I kissed her and she kissed back. I felt her arms wrap around neck as I licked her lip asking for an entrance. She accepted and I explored her mouth, leaving no space untouched. She broke from the kiss and whispered in my ear "Let's go to my bedroom" I smirked and carried her out of the water, but set her down as soon as we got out. "But I wanna touch you as soon as we get there" I whispered and zipped of her swimsuit. She removed my swim wear and I carried her to her bedroom. We stood in front of her bed as we continued the make out session

(Y/N)'s POV

As soon as we started talking, I knew it was meant to be. And know I'm here. He set me down on my bed as he fondled my boobs, I let out soft moans as I started playing with his hair. "Tsu-" I was saying when he cut me off and said "Call me Kei" I stayed silent for awhile and let out a moan while saying 'Kei'. I felt him smirk. He started sucking my nipples "A-Ah!" I moaned. He started playing with them and continued torturing me. "I've always wanted to do this" He whispered "Really?" I said looking at him. "Of course, your hotter than you're sister" He said. "Your boobs are a lit bigger, and I bet your pussy will taste better too" Be said and starting licking my wet slits. "K-Kei! Oh!" I moaned. He started massaging my sensitive bud and I started moaning like crazy. I shakily got up and managed to push him to the floor. He looked shocked and I whispered "My turn" also grinning to. He got onto the bed as I started licking his body, then making my way to his balls. I started fondling with them before sucking them. He let out moans and his voice mad me even more wet. I took a hold of his dick and started playing with it and licked the top of it. "Stop..teasing" He moaned, "Okay" I said and laid myself on the bed. He got up and lifted my legs, and without warning, he entered in me "A-Ah...Kei ah" I moaned. "F-Faster!" He kept going till we reached our climax, he pulled out before any cum could enter in my pussy. I opened my mouth as he cummed in it. I swallowed it all. I kissed him and got changed into our clothes. We heard the front door open and I said my goodbyes to him, before giving him one last kiss. I smiled and he left my bedroom

Extended Ending!

Kei visited often and soon broke up with (S/N), instead he got together with me. Now my sister just sits there whining like the b**** she is. She begs him to come back but of course he declines. So I live I happier life than she does!!!