The original materials used for Japanese bondage are hemp and jute. These materials do not stretch (when properly prepared) and have the property of "holding" a knot very well. Therefore they are very appropriate for bondage.
Because the preparation of hemp- and jute rope is a very time-consuming activity (boiling, drying, burning, oiling), many people are scared off to do this themselves.
If you are looking for good bondage rope without the hassle of preparing it before use we highly recommend BindMe's rope. It is completely prepared, a beautiful (wall)knot is added at each end to avoid unraveling and ready for use.