Light Speed Kicks are a signature technique for Admiral Borsalino, also known as Kizaru, in the One Piece series. The reason is that this form of extraordinary ability is a direct form of manifestation from Kizaru's powers with Pika Pika no Mi, which can create, manipulate, and transform into light at will. Such is Kizaru's combat style, founded on the idea of kicking at the speed of light, making him easily one of the strongest and most unpredictable fighters in the One Piece world.
Choppa at Light Speed Kicks is not only for mouthguard speed; rather, it is a display of creative application of powers from the Devil Fruit. This simply means that by turning parts of his body into light, Kizaru would be able to move at the speed of light, which is actually contrary to physics. He could provide such kicks with unequaled velocity and power to an enemy, hence becoming a nightmare to block or dodge.
For Light Speed Kicks, Kizaru transforms his leg into light while he is kicking. Assuming that at this state of matter, one effectively bypasses physical constraints—mass and inertia, mainly—it should let him avoid the natural impossibility of an object reaching light speed. However, how Kizaru really is able to maintain force in his kicks when in light form has yet to be well explained.
One of the most interesting things about Kizaru's Light Speed Kicks would be just how fast and powerful they really are. In reality, if something that has mass is going to accelerate to the speed of light, then that would mean it would take an infinite amount of energy to do so, which of course is impossible. Some fans have come up with the theory whereby, when Kizaru travels at the speed of light, he actually loses his mass, similar to how a laser works. This theory combines the fictional ability with known physics, stating that Kizaru's kicks could cause damage more comparable to high-energy laser beams than regular kinetic impacts.
Light Speed Kicks are especially strikingly visualized in the anime. Often, Kizaru just instantly moves, with his leg disappearing and reappearing at the point of impact, accompanied by a flash of light. This truly makes the incomprehensible speeds these attacks come in at almost teleporting to viewers.
Light Speed Kicks have been used and proved to be really effective in a number of critical fights within the series. In the Sabaody Archipelago arc, it was shown just how deadly the technique could be when used by Kizaru against the Supernovas. At such an intense speed, kicks like these are all but impossible to dodge or counter for any character, even those who have advanced Observation Haki.
Some fans and theorists have tried to work out the force of Kizaru's Light Speed Kicks hypothetically, assuming real-world physics. For example, if his leg—composed of approximately 17.555 percent of his total body weight—could actually travel at the speed of light, then the force of impact would be cataclysmically powerful. Please understand, however, that these are just computations against a manga series where Devil Fruit powers will never be estimated against real physics and speed of light in the same way. In fact, attacks at light speed in One Piece have been highly debated among fans. Some would have one believe that some abilities for Kizaru include light speed movement, through Light Speed Kicks; others would say the term may just be an exaggeration in the context of the story. It extends as far as debating other characters' speed feats, questioning how Kizaru's light speed fares against high-speed techniques from someone like Luffy or Sanji.
The most interesting of the Light Speed Kicks-related questions has to do with how Kizaru keeps control and accuracy at such extreme speeds. Some speculations want Kizaru to turn partially back to normal at the instance of impact in order to deliver the force of the kick effectively. Such a hypothesis tries to explain how Kizaru can stay destructive with his kicks but instead move at the speed of light.
The implications of Light Speed Kicks transcend the scope of it simply being a fighting skill for Kizaru. This technique, overall, within the One Piece world, represents the pinnacle of speed a character in the series can attain. Accordingly, it is the yardstick against which other high-speed abilities and techniques are often compared to, which goes on and off to feed into the power scaling discussions within the fan base.