A boy come in a shop and buy a pen that creates ,tranforms and comand everything he draw on the paper and other surfaces, including himself.
The boy initially use the pen to create a various objects, accidentaly his step-sister enter in his bedroom and watch the magic, but in the same time the boy has the idea of drawing a text on his step-sister for disappear the memory from the magic and leave the room. At this point, the boy try to draw a beutiful woman with huge boobs and huge ass, but he draw the step-sister face and she change her body in the same way of the drawing.In that moment , the boy saw the trasformation of his step-sister and try to comand his step-sister to have sex with him.
During the sex the step-sister changes another times becoming more sexy.
Idea by nico