Four Black Fogs Formation

is a barrier ninjutsu, performed by all of the Sound Four, used during the temporary "death" of those forcing the advancement of their cursed seal to its second level. The technique seals them in a coffin while the process takes place, and does not even allow the Byakugan to see inside. The Dark Sealing Method can be used for an additional layer of protection. The seal seems to be naturally lifted once the cursed seal has advanced to level two.