Mei creates a cloud of mist which she releases from her mouth. This mist has extremely corrosive properties, capable of melting even the bones of Sasuke Uchiha's Susanoo. The technique has an inherent disadvantage in that its effects are indiscriminate, limiting its usage to areas that do not contain allies. In the event that the mist escapes the containment area, the user can adjust the pH level of the mist to safer levels.
Though the mist is corrosive to all around it, the user seems to be immune to it, as Mei used it in an enclosed area without endangering herself.