Kamui

Kamui (神衣) are articles of clothing made entirely of Life Fibers. They have a degree of sentience and possess the ability to transform into extremely powerful and resistant armor suits. In order to do so, however, they need to feed on the user's blood. The amount of blood required to sustain a Kamui's powers depends on how well the user accepts the garment - if fully accepted, a Kamui can function nearly indefinitely with the blood taken during the initial activation. If worn by an undesired user, they can refuse to work altogether.

Only two "true" Kamuis have been shown in the anime so far, Senketsu and Junketsu. A third one, Shinra-Kōketsu, is shown finished in episode 23, though it is presumed that Shinra-Kōketsu is in a new class altogether.

Abilities
Wearing a Kamui grants the user immense power, compared to that of the Goku Uniforms. These garments have been shown to give the user the power to cause a percussion blast comparable to an atomic bomb. They also give the user enough power to leave craters in the earth and in stone, such as the wall surrounding Honnōji Academy.

Kamui can be extremely dangerous to the user, as in at least one occasion, a Kamui was seen completely disfiguring its wearer, causing the user to go berserk and have a distorted appearance. For this reason, Kamui in their activated state have a signature skimpy appearance to minimize surface contact with the user's skin, which reduces the chance of being overwhelmed by the Life Fibers.

Kamui Senketsu also has the ability to further transform in order to adapt to various situations, enabling abilities such as flight; Kamui Junketsu gained this ability after having some of Senketsu's Life Fibers implanted in it. It is unknown if Shinra-Kōketsu has this ability as well.

Shinra-Kōketsu
As it is referred to as "the ultimate Kamui", "Shinra (神羅) Kōketsu (纐纈)" is something entirely different from the first two Kamui. Unlike Junketsu and Senketsu, it is fashioned as a massive, Japanese-style wedding dress, that towers over either of them. This Kamui's design is to cover as much of the body as possible - something that Senketsu and Junketsu were designed not to do. Another aspect that sets Koketsu apart from the other Kamui is its Absolute Domination ability, that allows its user to neutralize other Life Fiber-based clothing, including other Kamui.