"Tool of demonstration?" Xue Yin wondered aloud as Nik nodded and sat on the edge of the bed occupied by Klas. She was soundly asleep even with the ball gag covering her mouth and Nik thought of the approach to start the lesson. Going too biological would ruin the mood while doing Klas too sadistically would also affect the over-all temperament of the latter portion of the session. He pulled the chairs towards the four girl with a simple manipulation of gravity while his fingers casually stroked Klas''s left thigh. A dildo was still vibrating within her snatch, but anyone would have gotten used to this form of ''torture'' by now. The area beneath her crotch was soaked in green.