Kikanshi

Kikanshi (気管支, Tranchea) is a Miasma Release technique only usable by Ryūku Sōga. First the correct handseals will be performed and the user will exhale into the air a fume that mixes with the air so is unable to determine the difference between the real air and this deadly fume that mixes with the air. When this air is inhaled, the targets lungs will begin to itch to a degree so annoying that some would even try clawing at their throats to get scratch their lungs. After that, their voice becomes scratchy and hoarse, then they aren't able to speak at all. For the finale of the deadly ninjutsu, the targets lungs will completely shut down and they will be unable to breathe altogether, eventually killing the target as they are out of breathe.