Tension literally means “tension”. Usually it refers to the rope tension, i.e. how tightly or loosely it is tied. In Yukimura-Ryû, however, it also refers to the emotional tension in the model and the bakushi. Both aspects influence each other and can be used to create intense moods.
The complex relationship between the rope tension and the emotional tension opens up its own playing field, which can already be used to design entire sessions. As in many other cases, the parameters tight/loose tightening and low/high emotional tension can be combined at will.