Kaizhai (開齋) Air Nomads are ethnic Air Nomads who conceal their origins, their airbending, and often their religion in response to the Air Nomad Genocide. Descending from the survivors of the Air Nomad Genocide, they can be found scattered throughout the Earth Kingdom and, to some extent, also in the Northern Water Tribe, continuing to hide from the Fire Nation. Kaizhai communities vary in the level of secrecy and degree of true or pretended assimilation they have undergone.

Unsurprisingly given their lack of safe contact with each other, Kaizhai groups are very diverse. Some continue to practice the Air Nomad religion openly in the Earth Kingdom or Northern Water Tribe, which is not particularly distinctive insofar as, particularly in the Northern and Western Earth Kingdom, there are significant populations of people who are of non-Air-Nation descent but who are believers in the Air Nomad religion as taught to them by missionaries. In this context, Kaizhai Air Nomads simply adopt the outward dress and peculiarities of their local coreligionists. With this practice involving little moral distress, these people have often completely integrated into their new settled communities and have often deliberately chosen to intermarry with those of different ethnicities but shared religious beliefs. Knowledge of the secret Air Nation heritage of some community members is kept from outsiders, but within it, trusted people may know. As the Fire Nation has sometimes persecuted non-Air-Nation practitioners of the Air Nomad religion, though, their position is considered relatively precarious, and they have usually fled in advance of the Fire Nation invasion when their communities are in its way. Since the term "Kaizhai" implies some relaxation of religious practices, this first group is arguably not really Kaizhai at all, and instead just refer to themselves internally as having "settled."

Whereas the "settler" crypto-Air-Nomads have abandoned nomadism but not their religion, the next group of Kaizhai typically refer to themselves as having "gone to ground." They retain a nomadic lifestyle, but have joined non-airbending nomad groups, typically non-settled Waterbending groups (sometimes even disguising their airbending as waterbending at a distance), or the nomadic peoples of the Western Earth Kingdom. (Some of these groups, such as the Abka and Yonggan, have had historical connections with the Air Nation and religious sympathies toward the Air Nomad religion.) The great majority of "gone to ground" Kaizhai have modified their outward religious practice, though some have joined with steppe Yonggan and Abka tribes who converted to the Air Nomad religion centuries ago during the Great Ri patronage of the Northern Air Temple. Many "gone to ground" Kaizhai no longer practice vegetarianism, though they may attempt to eat less meat than their non-crypto-air-nomad peers, fast, obtain vegetarian food where available, etc. The degree of assimilation pressure is high as most of these nomadic societies are high-context and expect their members to share in their traditional religion, diet, and practices (which might include violence against criminals, for example.)