Rin tapped her mechanical pencil on the table as she twirled her hair with her fingers. She requested Len to tutor her in the library for her Algebra exam next week. Len argued that they could always do it at home, but she pointed out that she won't be able to concentrate. Finally, Len sighed and agreed to teach her. But apparently, Rin had other plans.
They were sitting in the most unpopulated and isolated section of the library. She watched Len as he tried to teach her how to do the next problem.
"Got it?" Len looked at her for reassurance that she was still listening. "Yup." She nodded in response. When Len turned back to the problem, a small, unnoticeable smirk formed from Rin's lips as her mind wandered. Unfortunately for Len, Rin's mind wasn't the only thing wandering, but so were her hands.
Len felt something creeping along the surface of his pants, and shivered as it started caressing and massaging it.
Rin's hands caressed Len's thigh through his pants. She occasionally drew circles on the surface and neared his groin until it was only a few millimeters away from her hands. Rin's smirk grew wider when Len stiffened. He could feel his arousal growing tighter. Why of all places did she choose the library? Ugh. He mentally complained. Rin has been torturing him for the past few weeks.
Rin leaned in and breathed into his ear. Len resisted the urge to lung at her and do it right then and there. He stayed still knowing that if he showed any sort of reaction, Rin would not hold back, instead she would kick it up a notch. Rin, disappointed by his indifference, decided to tease him even more, just to see how long he would be able to keep this up.
She licked and nibbled his ear, as her right hand traveled from his thigh to his hair. Len closed his eyes as his body craved for more and his member threatened to release. Just as he thought it couldn't get any worse, her left hand suddenly unzipped his pants and pulled out his cock. She stood up and sat on his right leg and started moving her hand up and down slowly.
"Len, I wanna hear you moan." She leaned in and whispered seductively in his ear. "N-no. Not here." He managed. Her slow pumping was killing him and as much as he wanted her to go faster, that would only mean giving in. His hips bucked as his body begged for more. He cursed his own body for betraying his thoughts.
Rin took this as a sign. She started pumping as fast as she could. She bent down and licked the tip of his member while pumping the rest, and finally she took his whole arousal in her mouth and started pulling it in and out while sucking. "S-stop, Rin. I-I'm going to cum." Len pleaded as his fingers dug into the wooden chair and his hips bucked. Rin felt herself getting hot as she looked at her twin's flustered face. She realized she was getting wet down there, and it wasn't long before Len realized this too. She looked at Rin and smirked. Now it was his turn.
He put his hands on her shoulders and forced her onto the table. His lips crashed on hers and his tongue begged for entry. Rin opened her mouth and Len's tongue explored every single corner of her mouth.
"Mmm." Rin moaned into Len's mouth as their tongues danced and massaged each other, while Len's hands explored her body. When the kiss broke, a string of saliva connected them as they panted and gasped for air.
His hand reached her back and found the clasp of her bra. He didn't even have to think twice before unclasping it and taking it off. Len's lips once again met hers as Rin helped Len undress herself.
Len's lips moved from her lips to her jaw, down to her neck then to her shoulder, nibbling and licking in between the kissing. When Rin's upper body was finally stripped off of her final clothing, he started sucking on her soft and supple nipple while massaging the other breast. He nibbled on her nipples, earning occasional groan and moans from her. He moved down to her navel and reached her skirt. He flipped it up and noticed that she was not wearing any sort of normal lingerie. She was wearing a thong, the thong that he gave to her as a gift on their 16th birthday.
"You prepared for this." He said while licking her inner thighs. "You horny bitch." He smirked as he pulled down the thong with his teeth as far as he could. He parted her legs and rubbed his finger with her clit, teasing her enough to make her go mad.
He bent down and kissed her fold, then he started licking and sucking. His tongue going as deep as it could. "Nn. L-Len." He heard her moan as she arched her hips and made him go faster. He has already tasted her several times before but every time he did, she always seemed to taste better than the last time. He licked her folds for the last time and started rubbing her folds with his fingers again.
He then inserted one and started pumping, after a few minutes; he inserted another until all three fingers were inside her. He pumped his fingers in and out. By now, his arousal was throbbing so much that he knew that they had to do it now.
"Len… Do it. Now." Rin pleaded as her hips moved upwards and begged for more. Len positioned himself on top of her and entered her as soon as possible. As soon as Rin felt him inside her, she felt her walls tighten around his cock. His thrusts gradually got faster, always hitting her g-spot, until Rin's hips started bucking faster and Len matched his thrusts with her rhythm. Soon, he lost control and started humping her like crazy. His thrusts were so hard that they caused a crack on the table.
"Len!" Rin moaned in pleasure. They were both reaching their climaxes and they loved every moment of it. "R-Rin!" He shouted. He didn't care where they were anymore. He just wanted to feel her cum all over his arousal.
And with one final thrust, they both released. Rin loved the feeling of his seed sprouting into her and Len loved her juice all over his cock.
Len pulled out and sat on the chair. He closed his eyes and rubbed his temples. Suddenly, Rin pulled him by the necktie and kissed him. He kissed back and their kisses started to get deeper, and involve tongues, but Len pulled back. "Let's make a deal." He said, his faces still inches from hers.
She raised an eyebrow. "What do you mean?" She asked. "If you fail your math exam next week, you'll be my sex slave." He said, folding his arms across his chest.
"And If I get a perfect score?" She asked him. "Then, I'll be your sex slave." He smirked.
"Interesting… Deal." She said. "You better prepare yourself, Len Kagamine, because I'm definitely going to make you my sex slave."
AN: Sorry it's a bit crappy. It's not my best lemon. Hope you enjoyed it. :D