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. Instead of tombstones to honor the dead, the clan would instead plan trees for them. They were later found by Orochimaru, who used his cursed mark to partially stabilize their ability, Saying that he needed more research to perfect the process, the clan willing gave him multiple children as test subjects.