A crotch rope (also known as Matanawa or Sakura in Japanese bondage) is a bondage technique which involves the tying of rope around a woman's waist which is then passed between the labia to apply painful or pleasurable pressure to the female genitals. Crotch rope most commonly uses rope, but webbing, straps or a harness may also be used.
A crotch rope may be tied over clothing or directly onto the skin, and can be worn under clothing or in full view. While crotch ropes are most commonly intended for women, specific variations exist for males.
A crotch rope can also be used as an unsophisticated type of chastity belt.
Crotch rope Wikipedia
Typically, the ropes pass between the labia majora or deeper through the cleft of the vulva. Knots can be tied in the rope to apply specific pressure to the anus or clitoris. It's usually fixed in place by tying it to a rope around the waist just above the hips or by tying the two ends to another fixture. It is also used in BDSM activities especially on female submissives most commonly as a part of tease and denial.
Two ropes passing between the groins on either side of the labia may be used instead of the center rope or in addition to it. In the latter case the ropes will press the labia against the center rope for additional pain/discomfort. For abrasion play if the rope is not tied to the waist it can be moved forward and backward between the labia or the subject can be made to walk across it.
The ropes may be wrapped tightly around waist and tied off in front, fed down across the genitals, then pulled back up behind and tied to other cords wrapped around the wrists, doubling as a cinch to tighten them further. This allows the rope bound person some ability to vary pressure on the genitals (often causing sexual stimulation) at the cost of reduced freedom of movement. If such a cord is pulled extremely tight the wrists and arms will have very little freedom of movement and the hands will be firmly forced in contact with the butt, particularly when combined with Elbow Bondage.
Sometimes, a crotch rope is combined with other bondage techniques, such as breast bondage or elbow bondage.