Tanjirou got up the second he heard someone knocking at his door. As he expected, it was Nezuko. They had already been dealing with her heats for nearly seven months, and it seemed that they'd only last five days at most, and that didn't come back until at least a month had passed.
Luckly for his baby sister, he knew just how to make it better.
"You're in heat again?" he asked, getting a cute little nod as an answer. He opened up his arms and waited for her to come to him.
His sister took off her muzzle, running straight to him and pulling him in for a deep, fiery kiss, then just rested her head on his shoulder as she held him tight. Tanjirou ran his fingers through her soft, dark hair as he rubbed her back.
"I'll take good care of you, Nezuko" he assured her, kissing her forehead, then pressing his lips to hers again, giving a little nip to the lower one, then letting his tongue toy with hers. Their hands were exploring each other's bodies like it was the first time again - they just couldn't hold back the passion they felt. They needed to feel this. Being as close as possible, skin on skin, safe in a loving embrace.
Tanjioru carried her to the bed, gently laying her down and getting on top of her. The second he kissed her again, Nezuko switched their positions and started tearing his clothes off of him, making him grin. He got the message: she needed it bad, and she needed it now.
Well, who was he to deny her that, especially when he loved it just as much as she did?
He helped his sister undress him, then they did the same to her, immediately pulling her to his lap, one hand on her waist, the other rubbing her clit. He buried his face on the curve of her neck, kissing it, then breathing in her sweet scent on her skin and hair. Nezuko was holding on to his shoulders, moaning right in his ear, licking the lobe then kissing his cheek.
Tanjiou brought his head lower and Nezuko shifted on his lap, going from a sitting position to being on her knees, grabbing his hair, keeping him there as he kissed, licked, bit, and sucked on her breasts, covering it in teeth marks, bruises and hickeys. Her soft little moans only encouraged him to keep doing what he was doing.
He started fingering her, his thumb still stimulating her clit, causing her to tremble and shake in his arms. He a second finger, then another, making her hiss. He hooked his fingers inside her, hearing the desperate cries of pleasure that were escaping past her lips - lips he didn't hesitate to capture with his own in another kiss. Nezuko let her tongue toy with his, before quickly dominating the kiss, demanding more from him, which he would gladly give.
She pulled away, allowing him to see her pretty face as he brought her closer to orgasm. Tanjirou loved looking deep into his little sister's pink eyes and seeing her innocence mixed up with that diabolical lust that always threatened to consume them both. Nezuko closed her eyes, mouth falling open and cheeks burning in a bright, adorable shade of red, body convulsing and walls squeezing his fingers as she reached her climax. Tanjirou loved this too - that moment when her need for him was tamed, but not satisfied.
He undressed his sister and she helped him take his own clothes off, climbing back into his lap and lining up his cock against her wet pussy. They both moaned as she inserted the head inside herself and Tanjirou grabbed her hips, pushing his entire length into her cunt. Nezuko embraced and kissed him, bouncing up and down on his cock as his hands grabbed her ass.
His sister broke the kiss, moaning in his ear before nipping at the lobe then kissing his neck. He groaned and switched positions, making her lie underneath him as he fucked her rough, slow, and deep, having to hold back so he wouldn't come too fast.
Pulling away slightly, Tanjirou lifted up one of his sister's legs, allowing him to go as deep as possible. Nezuko grabbed and tore the sheets as he rubbed her little clit again. She buried her nails in the mattress, calling out his name. Tanjirou was too consumed by lust to even remember that they were supposed to keep quiet to avoid getting caught. If anyone had been near his room, they would have definitively heard them and known exactly what they were doing.
He didn't care. He couldn't care about anything when he was with her.
How could anything be more important than the sight in front of him? His baby sister trashing around in bed, begging desperately for the pleasure that only he could bring her, calling out his name in between her moans and grunts, her hair a mess, her hips moving faster and faster, her whole body wanting him to fuck her as hard as wanted, for as long as he wanted... nothing could compare to this. He wouldn't care if the whole world started crumbling around them, and Nezuko clearly felt the same.
Suddenly, his sister threw her head back, screaming as her body started shaking violently. Tanjirou kept thrusting into her, fucking her through her orgasm before finally letting himself fall. He lied on top of her, kissing her face and hugging her tight, watching her relax and slowly drifting into sleep.
He didn't get up to lock the door once he remembered he had not taken care of that 'little' detail, simply snuggling him little sister and whispering a sweet 'I love you' against her dark hair.
She was his, just as he was her's. Always had been, always would be.