The 15 year old boy, Yo`av, was just lying in his bed masturbating, when a triple knock was heard upon his bedroom-door.
Knowing this to be the signal of his beLoved younger sister Maya, he shout her to come in, while partly-covering his hard erected member. The tall and skinny 12 year old brunette stepped in, wearing nothing but a skimpy nightgawn, which just barely covered her small ass and slowly-developing tits; she knew her effect upon her big brother, and wanted to play on with her luck, pushing it to its furthest reaches.
"Hi Yovi", said Maya, "what's up?"
"Nothing much", replied her bro.
"I can see it is much alright", smiled his sister wickedly, pointing at the small tent of his light summer-blanket.
"You're invited to check", winked Yo`av at her, at which she just went, threw the blanket a hell away onto the floor, and seized his boner forcibly with her small right hand. "Auch!!" yell her brother, "don't do it that strongly!" "Sorry", said his sister and began carressing and massaging his hard-on...
And pretty soon, he could not bare it anymore. "I'm cumming!!" the boy cried out - and out came his boyish semen, in small, yet wild gushes, of adorable white streams, right upon his little sister's sweaty hands. "Licked it", he breathed a command at her, excited - and always willing to obey, the 12 year old girl licked all her brother's love-potion off from her hands, then from his Penis - and then, went on to bath his shrinking member in her loving, sweet mouth... till it was stiff as a rock once again.
And then, Yo`av just felt, hje did not give a shit anymore.
His sister wished to remain a virgin, for the very least until her 15th birthday; but, her brother just HAD to have her...

And he did.

"NO!!!!" cried Maya, tears forming in her eyes, then gushing down her cheeks. "No, please - let me just suck you off Yovi, PLEASE!!" But, he could not restrain himself any longer. "Sorry sis", breathed her brother, "I must HAVE you NOW!!"