Iburi Clan

The is a seclusive clan living underground in the Land of Fire. They have the ability to become smoke at will and still physically interact. However, this ability is imperfect, causing them to occasionally transform unintentionally. In their smoke form, they are vulnerable to wind as it will cause them to disperse permanently and die. Because of that, clan members tend not to have long lives, forced to live confined in caves or places where the wind is practically nonexistent. Instead of tombstones to honour the dead, the clan would instead plant trees for them, believing their deceased souls would watch over them. They were later found by Orochimaru, who used his cursed seals to partially stabilise their ability. Claiming he needed more research to perfect the process, the clan willing gave him multiple children as test subjects, as the ability is more pronounced the younger the user is.

Trivia

 * means to smoke.