Tandokuhan

The Poisoner was a dangerous troublemaker who was based in Shinjuku. However it was reported that the Poisoner was among the troublemakers that were killed or in custody of the Materials Compiling Group No.3. However before passing away the Poisoner took on a pupil named [Kazami Asaura](https://anilist.co/character/302204/) who would don their signature gas mask and become a formidable presence in the underworld.