Gripping her shaft with her slender fingers, Rin traced her rock hard penis over Sakura's shapely pink lips. The luxurious feel of them against her sensitive cockhead made her insides clench with anticipation.
"Please Nee-san," Sakura whispered breathlessly. "Please don't tease me."
"Who's teasing who?" Rin asked, sliding the bulbous head against her sister's soft cheek. The spongy mass was swollen with arousal. She tried to maintain a frown as Sakura turned and pecked the side of her dickhead cheekily. It looked so sexy and felt so good that Rin let out a slight grunt. Her dick flexed upwards and flicked against the bangs of Sakura's purple hair.
Sakura smiled up at her older sister saucily. "Do you like that?" She kissed it again, the same spot, longer this time, almost sucking at the sensitive skin. The feeling of her full lips was divine.
"Sakura..." Rin warned.
"Hm? Do you like my lips on you?"

Rin grinned, feral, for a second, and a mix of fear and lust spread across Sakura's face.
Her heartbeat sped up as she waited for Rin to explode, become angry enough to ravage her.
"Yes." Rin said. She stroked Sakura's cheek with the back of her fingers. "Now hurry up and suck me so I can screw the grail out of you."
Sakura giggled. "As you command, Nee-san...." Leaning in, she began at the base, kissing once. An inch higher, she kissed the shaft again, the languid smack loud in Rin's lust-dulled ears. Inch by inch she kissed the length of Rin's long, thick cock, until she reached the head. She stretched her mouth open cutely. "Mwaaaaah..." she went, sticking out her wet tongue, before slobbering over the shaft, all reserve gone.

Rin groaned cutely, one hand on Sakura's head as she pleasured her with her hot, talented mouth.

"Mmmmm...do you have a lot of cum today, Nee-san...?" Sakura asked, resting the wet weight of Rin's length on her face and against her nose as she kissed the base of the shaft.

Thoughts?