Sentenashi also known as Kiri-oboeru is a technique where user takes full advantage of their control over the battle paths to reverse time when a response to an opponent's actions is conducted so that their "response" to the attack takes place before the opponent's action ever took place. Because this is the act of quite literally performing a move that is sent into the past, the idea of speed and strength are negligible for if the action that is sent back in time in some way sends time off into a tangent where the succeeding action would be impossible, the opponent's action will be completely neutralized.
Sentenashi (に先手なし, "No First Strike") refers to a principle that states in martial arts, one does not strike first, for it is against the notion of self-defense. By manipulating the battle paths, there is no need for a first strike. While Kiri-oboeru is an old samurai saying that means, ‘Strike down your enemy, and learn.’ The term is used to explain training on the road and in battle sharpens ones instincts to a razor edge and teaches them to fight with the whole of their being. Something that training in a dojo doesn’t provide; both names apply.
From opponents perspective it is as if user is rejecting the destiny of a battle through his own martial will, thereby spitting upon the notion of destiny itself; a fitting ability for a craft believed to have been born by the idea of challenging a greater power than oneself. However from user’s perspective it’s like a memory coming from someone else allowing them to turn back time in order to continuously retry different battle strategies until they achieve victory, just like the samurai of old.